National Geochemical Database: Sediment

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title: National Geochemical Database: Sediment
Abstract:
Geochemical analysis of sediment samples from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are of stream sediment in the continental US and Alaska. Samples were collected and analyzed over many decades, beginning in the 1960s, though some samples may have been collected earlier.
  1. How might this data set be cited?
    U.S. Geological Survey, 2016, National Geochemical Database: Sediment: U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -179.36667
    East_Bounding_Coordinate: 179.9425
    North_Bounding_Coordinate: 74.90833333
    South_Bounding_Coordinate: -49.81222222
  3. What does it look like?
    https://mrdata.usgs.gov/ngdb/sediment/ngdbsed-large.png (PNG)
    Schematic map showing sample density in the conterminous US, (768 x 512 pixels)
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 06-Dec-1962
    Ending_Date: 16-Nov-2005
    Currentness_Reference:
    Dates samples were submitted for analysis
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Entity point (335026)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in decimal degrees. The horizontal datum used is World Geodetic System 1984.
      The ellipsoid used is WGS 84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
  7. How does the data set describe geographic features?
    datadxny
    Data dictionary, explaining tables and fields (Source: USGS)
    id
    Record ID.

    Row identifier within datadxny table. Integer values. Integer of width 8. (Source: this data release)
    Range of values
    Minimum:1
    Maximum:67
    Resolution:1
    tblorder
    Table order.

    Order in which this table should appear in some presentations. Integer values. Integer of width 8. (Source: this data release)
    Range of values
    Minimum:1
    Maximum:4
    Resolution:1
    tblname
    Table name.

    Name of the table. Textual values of no more than 20 characters. (Source: this data release) Text as used by the database management system
    number
    Ordinal position.

    Order in which this field occurs in the database. Integer values. Integer of width 8. (Source: this data release)
    ValueDefinition
    (no value)The table row describes the table as a whole rather than one of its fields
    Range of values
    Minimum:1
    Maximum:30
    Resolution:1
    label
    Field label.

    Label of the field in the database. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    (no value)The table row describes the table as a whole rather than one of its fields
    Field name as used internally in the database software
    category
    Category.

    General category of information provided by the contents of the field. Textual values of no more than 50 characters. (Source: this data release)
    ValueDefinition
    (no value)The table row describes the table as a whole rather than one of its fields
    Sample identificationNames, numbers, or other identifiers of the samples
    Processing informationCharacteristics of the handling, processing, or analysis of the samples
    Geographic locationInformation indicating the location from which the sample was collected
    Site characteristicsInformation describing the environment from which the sample was taken
    Sample characteristicsDescriptive characteristics of the sample itself
    Chemical analysisResults of analysis of the sample, typically quantitative
    MetadataInformation used to organize the data in this collection
    short_desc
    Short description.

    Descriptive name of the field used in some presentations, not constrained by rules affecting the label. Textual values of no more than 40 characters. (Source: this data release)
    ValueDefinition
    (no value)The table row describes the table as a whole rather than one of its fields
    description
    Description.

    Longer description of the purpose and contents of the field or table. Textual values of no more than 4096 characters. (Source: this data release) Plain text, not abbreviated
    link
    Link.

    URL providing more information about the field. Textual values of no more than 96 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 67 records have no value for link.
    origin
    Origin of field.

    Abbreviation of an organization, data set, or other entity responsible for defining the field. Textual values of no more than 12 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 67 records have no value for origin.
    sqltype
    SQL type.

    Data type of the field as used in the database. Textual values of no more than 8 characters. (Source: this data release)
    ValueDefinition
    (no value)the table row describes an entire table rather than a single field
    integerField contains integer values
    character varyingField contains character values of varying length
    double precisionField contains floating-point values
    dbftype
    DBF field type.

    Data type of the field when expressed in DBF. Textual values of exactly 1 character. (Source: this data release)
    ValueDefinition
    Ccharacter data
    Nnumeric data
    width
    Field width.

    Field width when expressed in DBF. Integer values. Integer of width 8. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 4 records have no value for width.
    Range of values
    Minimum:1
    Maximum:4096
    Resolution:1
    prec
    Precision.

    Precision of the field (places to right of decimal) when expressed in DBF, only for numeric fields. Integer values. Integer of width 8. (Source: this data release)
    ValueDefinition
    (no value)The field contains character data, or the row describes the table as a whole rather than an individual field
    Range of values
    Minimum:0
    Maximum:6
    Resolution:1
    units
    Units of measure.

    Units of measure of the field values. Textual values of no more than 64 characters. (Source: this data release)
    ValueDefinition
    (no value)The field contains character data, the units are specified in a separate field of the table, or the row describes the table as a whole rather than an individual field
    main
    Sample location, characteristics, and general methods of collection and analysis (Source: USGS)
    lab_id
    Lab ID.

    Unique identifier assigned to each submitted sample by the Sample Control Officer of the analytical laboratory that received the sample. Textual values of no more than 10 characters. (Source: this data release) Alphanumeric identifiers without intrinsic scientific significance
    field_id
    Field ID.

    Field identifier assigned by the sample collector, sometimes modified or truncated when keypunched to fit the available field width. Textual values of no more than 16 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 1877 records have no value for field_id.
    Alphanumeric identifiers without intrinsic scientific significance
    job_id
    Job ID.

    Laboratory batch identifier assigned by the Sample Control Officer of the analytical laboratory for each batch of samples received. Textual values of no more than 10 characters. (Source: this data release) Alphanumeric identifiers without intrinsic scientific significance
    submitter
    Submitter.

    Name of the individual(s) who submitted the sample in a batch to the laboratory for analysis; not necessarily the sample collector. Textual values of no more than 80 characters. (Source: this data release) Names, unabbreviated
    date_collect
    Date collected.

    Date sample was collected, as reported by submitter, mm/dd/yyyy. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 318846 records have no value for date_collect.
    While dates are generally formatted as month/day/year, the number of digits in these components varies, and some values are expressed as a range
    date_submitted
    Date submitted.

    Date sample was submitted to Sample Control for initial database processing prior to sample prep and analysis, mm/dd/yyyy. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 9360 records have no value for date_submitted.
    Generally these dates follow the format month (2 digit) / day (2 digit) / year (4 digit)
    project_name
    Project name.

    Project name, if known, that funded the collection and analysis of submitted samples. Textual values of no more than 80 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 169813 records have no value for project_name.
    Names, typically unabbreviated, sometimes with question marks
    state
    State.

    Abbreviation of state from where the sample was collected; only used within the United States. Textual values of no more than 2 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 12038 records have no value for state.
    Formal codeset
    Codeset Name:U.S. Postal Service abbreviations for states and territories
    Codeset Source:Post Office Department Publication 59, Abbreviations for Use with ZIP Code, October 1963, revised 1969.
    country
    Country.

    Country from where the sample was collected. Textual values of no more than 32 characters. (Source: this data release) Place or area names, mostly unabbreviated, including bodies of water.
    lat_wgs84
    Latitude (WGS84).

    Latitude coordinate of sample site converted, if necessary, to the WGS84 datum, reported in decimal degrees. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-49.81222222
    Maximum:74.90833333
    Units:decimal degrees
    long_wgs84
    Longitude (WGS84).

    Longitude coordinate of sample site converted, if necessary, to the WGS84 datum, reported in decimal degrees. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-179.36667
    Maximum:179.9425
    Units:decimal degrees
    datum_orig
    Original datum.

    Original reference datum, when recorded, for the latitude and longitude coordinates of the sample site. Values in (parentheses) are a best estimate for original datum values that were not recorded. Textual values of no more than 64 characters. (Source: this data release)
    ValueDefinition
    European 1950European 1950 (which variant is not specified)
    Indonesian 1974Indonesian 1974
    NAD27North American Datum of 1927
    NAD83North American Datum of 1983
    SAD69South American Datum 1969
    WGS84World Geodetic System 1984
    lat_orig
    Original latitude.

    Original latitude coordinate of sample site as supplied by the sample submitter, reported in decimal degrees. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-49.81222222
    Maximum:74.90833333
    Units:decimal degrees
    long_orig
    Original longitude.

    Original longitude coordinate of sample site as supplied by the sample submitter, reported in decimal degrees. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-179.36667
    Maximum:179.9425
    Units:decimal degrees
    coord_prec_est
    Precision of coordinate location.

    Estimated precision of coordinates that were originally supplied by the sample submitter, reported to the nearest second, minute, degree, foot, or meter. Textual values of no more than 32 characters. (Source: this data release) Explanatory text, not abbreviated
    depth
    Depth.

    Depth from the surface at which the sample was collected; units are specified by the submitter. Textual values of no more than 80 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 318708 records have no value for depth.
    locate_desc
    Location description.

    Sample location description as supplied by the sample submitter. Textual values of no more than 256 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 302469 records have no value for locate_desc.
    Explanatory text, not abbreviated
    sample_source
    Sample source.

    Sample source, parent material, or indication of the land cover. Textual values of no more than 40 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 42509 records have no value for sample_source.
    Short descriptive terms for the environment, not abbreviated, in some cases expressed as a set of closely related terms separated by slash to mean "or".
    method_collected
    Method of collection.

    Method used to collect the sample. Textual values of no more than 20 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 72265 records have no value for method_collected.
    channelmaterial taken from a trench or linear excavation
    compositematerial combined from several discrete takings
    othercollection method not one of those described by this field
    single/grabmaterial from a single act of taking at a single location
    sngl/cmpst/chnlcollection may have been single, composite, or channel
    unknowncollection method not known
    primary_class
    Sample medium.

    Sample media primary classification. All values in the sediment dataset equal SEDIMENT. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    sedimentunconsolidated earth materials, typically deposited by streams or other bodies of water
    specific_name
    Specific name.

    Specific name or description of material that was submitted. Textual values of no more than 40 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 316600 records have no value for specific_name.
    Text indicating material, not abbreviated
    addl_attr
    Notes on sample.

    Comment field that includes submitter supplied comments and text for additional attributes that are no longer maintained separately. Textual values of no more than 256 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 59308 records have no value for addl_attr.
    Text may contain identifiers, description, place names, or feature types
    geologic_age
    Geologic age.

    Geologic age of the sample (or possibly the parent material) as supplied by the submitter. Textual values of no more than 64 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 300722 records have no value for geologic_age.
    Geologic periods, sometimes specified as a range of periods using hyphen
    stratigraphy
    Stratigraphy.

    Stratigraphic formation name as supplied by the submitter. Textual values of no more than 256 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 324030 records have no value for stratigraphy.
    Formation names (sometimes abbreviated) or stream names
    mineralization
    Mineralization.

    Indication of or type of mineralization associated with the sample. Textual values of no more than 40 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 333655 records have no value for mineralization.
    Short descriptive text indicating general form or process of mineral concentration, not abbreviated
    prep
    Preparation.

    Description of sample preparation procedures used prior to analyzing the sample. Textual values of no more than 256 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 327215 records have no value for prep.
    Descriptive text, may include program name such as NAWQA to indicate adherence to program preparation protocols
    mesh_size
    Sieve mesh size.

    Mesh size used or final size fraction that was analyzed. Textual values of no more than 64 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 210824 records have no value for mesh_size.
    Descriptive text, may include procedural details such as "dry sieved"
    collection_protocol
    Collection protocol.

    Standard or published protocol used for collecting and preparing the sample. Textual values of no more than 64 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 334871 records have no value for collection_protocol.
    NAWQA sediment collection protocolCollection procedures followed guidelines of the National Water Quality Assessment program
    previous_job_id
    Previous job ID.

    Previous laboratory batch identifier, used when a sample was resubmitted in a new batch for further analyses. Textual values of no more than 20 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 333343 records have no value for previous_job_id.
    Alphanumeric identifier without further scientific significance
    previous_lab_id
    Previous lab ID.

    Previous laboratory-assigned Unique identifier, used when a sample was resubmitted for further analyses and given an new Lab ID. Textual values of no more than 20 characters. (Source: this data release)
    ValueDefinition
    (no value)Information not available for this record. 331049 records have no value for previous_lab_id.
    Alphanumeric identifier without further scientific significance
    chemistry
    All chemical analyses recorded for the sample, with analytical method, measured values, and qualifiers to indicate where a measured value was outside the reliable determination limits of the method (Source: USGS)
    rec_id
    This field contains the unique sequence number by which the given analysis can be related to the corresponding record in the master database from which these records were drawn. Consequently this value would be used to identify records that required correction in the master database, if necessary.

    Integer values. Integer of width 8. (Source: this data release)
    Range of values
    Minimum:45225
    Maximum:54405511
    Resolution:1
    lab_id
    Lab ID.

    Unique identifier assigned to each submitted sample by the Sample Control Officer of the analytical laboratory that received the sample. Textual values of no more than 10 characters. (Source: this data release) Alphanumeric identifiers without intrinsic scientific significance
    species
    Chemical species.

    Element, oxide, compound, or property that was determined or measured by the laboratory. Textual values of no more than 40 characters. (Source: this data release)
    ValueDefinition
    LiLithium
    BeBeryllium
    BBoron
    C_totCarbon (total)
    C_orgCarbon (organic)
    C_crbCarbon (carbonate)
    CO2Carbon dioxide
    NNitrogen
    FFluorine
    NaSodium
    MgMagnesium
    AlAluminum
    SiSilicon
    PPhosphorus
    SSulfur
    ClChlorine
    KPotassium
    CaCalcium
    ScScandium
    TiTitanium
    VVanadium
    CrChromium
    MnManganese
    FeIron
    CoCobalt
    NiNickel
    CuCopper
    ZnZinc
    GaGallium
    GeGermanium
    AsArsenic
    SeSelenium
    BrBromine
    RbRubidium
    SrStrontium
    YYttrium
    ZrZirconium
    NbNiobium
    MoMolybdenum
    RuRuthenium
    RhRhodium
    PdPalladium
    AgSilver
    CdCadmium
    InIndium
    SnTin
    SbAntimony
    TeTellurium
    IIodine
    CsCesium
    BaBarium
    LaLanthanum
    CeCerium
    PrPraseodymium
    NdNeodymium
    SmSamarium
    EuEuropium
    GdGadolinium
    TbTerbium
    DyDysprosium
    HoHolmium
    ErErbium
    TmThulium
    YbYtterbium
    LuLutetium
    HfHafnium
    TaTantalum
    WTungsten
    ReRhenium
    OsOsmium
    IrIridium
    PtPlatinum
    AuGold
    HgMercury
    TlThallium
    PbLead
    BiBismuth
    PoPolonium
    ThThorium
    UUranium
    SplWtAuWeight of sample used for gold analysis
    SplWtFAWeight of sample used for fire assay analysis
    unit
    Units of measure.

    Unit of measurement associated with the accompanying concentration value. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    ggrams
    pctpercent by weight
    ppmparts per million by weight
    qvalue
    Measured value.

    Qualified concentration value for the associated Species and reported in the associated Unit. Values less than the lower limit of determination are negative while values greater than the upper limit of determination have a .1111 suffix. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-200000
    Maximum:584300
    qualifier
    Qualifier of measurement.

    Qualifier (L, N, G, <, or >) for censored data. Only used in the All Chemistry tables. Textual values of no more than 1 characters. (Source: this data release)
    ValueDefinition
    LThe measured value was less than the lower limit of determination by the method
    NThe chemical species was not detected by the method
    GThe measured value was greater than the analytical method's upper determination limit
    (less-than symbol)The measured value was less than the lower limit of determination by the method
    (greater-than symbol)The measured value was greater than the upper limit of determination by the method
    (no value)The measured value is within the range of values for which the analytical method is considered valid.
    amethod
    Analytical method.

    Analytical method code (abbreviation) for the method used to determine the associated Species. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    AA_CVMercury by cold-vapor atomic absorption spectrometry after multi-acid digestion and solution.
    AA_CV_WOMercury by wet oxidation and cold-vapor atomic absorption spectrometry ("flameless"); HNO3-H2SO4-HClO4 digestion, Hg aerated to silver screen, amalgamator heated in furnace, Hg vapor measured in AAS.
    AA_F_AZ_Fuse_PSilver, arsenic, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by flame atomic absorption spectrometry after partial digestion by K2S2O7 fusion, HCl-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_AZ_H2O2_PSilver, arsenic, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by flame atomic absorption spectrometry after partial digestion with HCl-H2O2-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_AZ_HCl_PSilver, arsenic, bismuth, cadmium, antimony and zinc by flame atomic absorption spectrometry after partial digestion by HCl-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_FuseMajor and minor elements by flame atomic absorption spectrometry after LiBO2/Li2B4O7 fusion digestion.
    AA_F_Fuse_PMolybdenum and antimony by flame atomic absorption spectrometry after K2S2O7 (Mo) or NH4I (Sb) fusion, partial acid digestion, and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HBrGold and tellurium by flame atomic absorption spectrometry after HBr-Br2 digestion and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HCl_OE_PAntimony by flame atomic absorption spectrometry after NH4I fusion, digestion with HCl, and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HFMajor and minor elements by flame atomic absorption spectrometry after multi-acid digestion with HF.
    AA_F_HNO3_PSilver, bismuth, cadmium, cobalt, copper, nickel, lead and zinc by flame atomic absorption spectrometry after partial digestion with hot HNO3.
    AA_FESodium and potassium by flame emission spectrometry (flame photometry) after HF-HClO4 dissolution or LiBO2 fusion.
    AA_GF_HBrGold and tellurium by graphite furnace atomic absorption spectrometry after HBr-Br2 digestion and selective organic extraction with Aliquat 336-MIBK.
    AA_GF_HFArsenic, gold, bismuth, indium, antimony, tellurium and thallium by graphite furnace atomic absorption spectrometry after multi-acid digestion with HF and selective organic extraction with Aliquat 336-MIBK.
    AA_GF_STThallium by graphite furnace atomic absorption spectrometry after Na2O2 sinter, HCl-HNO3 dissolution, and selective organic extraction with DIBK.
    AA_HG_AcidSelenium by flow injection or continuous flow hydride generation-atomic absorption spectrometry after digestion with HNO3-HCl-H2SO4-KMnO4.
    AA_HG_HFArsenic, antimony, selenium and tellurium by flow injection or continuous flow hydride generation-atomic absorption spectrometry after multi-acid digestion with HF.
    AA_HG_STArsenic and antimony by flow injection or continuous flow hydride generation-atomic absorption spectrometry after Na2O2 sinter digestion.
    AA_TRMercury by thermal release and atomic absorption spectrometry after heating (Vaughn-McCarthy method).
    AA_TR_WMercury by thermal release and atomic absorption spectrometry after heating (Vaughn-McCarthy method) and use of a willemite screen.
    AES_AR_PMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after partial digestion with aqua regia.
    AES_AZ_PSilver, arsenic, gold, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by inductively coupled plasma-atomic emission spectrometry after partial digestion with HCl-H2O2.
    AES_Acid_PMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after unknown partial acid digestion.
    AES_FuseMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after Li2B4O7 fusion digestion.
    AES_HFMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after digestion with HF-HCl-HNO3-HClO4.
    AES_HF_REERare earth elements by ion exchange and inductively coupled plasma-atomic emission quantitative spectrometry after HF-HCl-HNO3-HClO4 digestion.
    AES_IEMolybdenum, niobium and tungsten by inductively coupled plasma-atomic emission quantitative spectrometry after HF-HCl-HNO3-HClO4 digestion and ion exchange separation.
    AES_STMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after Na2O2 sinter digestion.
    CB_CHNCarbon, hydrogen and nitrogen by gas chromatography/thermal conductivity (CHN elemental) analyzer after combustion.
    CB_IRCCarbon and sulfur by infrared detection after combustion.
    CB_TCTotal carbon and organic carbon by thermal conductivity detection after combustion.
    CB_TTSulfur by iodometric titration after combustion.
    CM_AcidBromine by colorimetry after acid digestion.
    CM_Acid_PArsenic by modified Gutzeit apparatus confined-spot method colorimetry after partial digestion in KOH-HCl and chemical separation.
    CM_FuseMajor and minor elements by colorimetric spectrophotometry after fusion digestion.
    CM_Fuse_PMolybdenum and antimony by colorimetry after partial digestion by K2S2O7 fusion (Mo) or NaHSO4 fusion-HCl digestion (Sb, rhodamine B).
    CM_HFMajor and minor elements by colorimetric spectrophotometry after multi-acid digestion with HF.
    CM_HNO3_PCopper, lead and zinc by colorimetry after partial digestion with HNO3.
    CM_HSFFluorine by chemical separation and colorimetric spectrophotometry; chemical separation to fluorosilicic acid (H2SiF6), converted to silicomolybdate, reduced to Mo blue.
    CM_PC_PUranium by paper chromatography after partial digestion with HNO3.
    CM_SDDCArsenic by colorimetric spectrophotometry after digestion in HF-aqua regia and chemical separation with SDDC.
    CM_STChloride by colorimetric spectrophotometry after Na2CO3 and ZnO sinter digestion.
    CM_ST_PTungsten by colorimetry after partial digestion with carbonate sinter.
    CPOrganic carbon, carbonate carbon and totals by computation.
    DNUranium and thorium by delayed neutron activation counting.
    EDXMinor elements by energy-dispersive X-ray fluorescence spectrometry.
    ES_QMajor and minor elements by quantitative emission spectrography.
    ES_SQMajor and minor elements by semi-quantitative emission spectrography.
    FA_AAGold, silver and platinum group elements by graphite furnace atomic absorption spectrometry after PbO fire assay chemical separation.
    FA_DCGold by direct current plasma-atomic emission spectroscopy or atomic absorption spectrophotometry after PbO fire assay chemical separation.
    FA_ESGold and platinum group elements by direct-current arc quantitative emission spectrography after PbO fire assay chemical separation.
    FA_MSPlatinum group elements by inductively coupled plasma-mass spectrometry after NiS fire assay chemical separation.
    FL_Acid_PSelenium by acid digestion and fluorometry; HNO3 digestion, H2O2 added, HClO4 digestion, HCl reduced, reacted with 2,3-diaminonapthalene.
    FL_HFBeryllium, tin and uranium by fluorometry after multi-acid digestion with HF.
    FL_HNO3Selenium by fluorometry after digestion with HNO3-H3PO4.
    GVDensity, moisture and weight by gravimetry; ash or loss on ignition by weight loss after heating at 900 degrees C.
    GV_WOOrganic carbon, as CO2, by wet oxidation and gravimetry; H2SO4 digestion, oxidized with CrO3-H2SO4, CO2 collected on ascarite; data from "Energy Group SP Open File UGR-068".
    ISE_FuseChloride, fluoride and iodide by ion specific electrode after fusion digestion.
    ISE_HFChloride by ion specific electrode after multi-acid digestion with HF.
    MS_AR_PMajor and minor elements by inductively coupled plasma-mass spectrometry after partial digestion with aqua regia.
    MS_HFMajor and minor elements by inductively coupled plasma-mass spectrometry after HF-HCl-HNO3-HClO4 digestion.
    MS_STMajor and minor elements by inductively coupled plasma-mass spectrometry after Na2O2 sinter digestion.
    MS_ST_REERare earth elements by inductively coupled plasma-mass spectrometry after Na2O2 sinter digestion.
    NA_LCMajor and trace elements by long count instrumental neutron activation analysis; no digestion/extraction necessary.
    NA_SCMajor and trace elements by short (abbreviated) count instrumental neutron activation analysis; no digestion/extraction necessary.
    TC_JrmMercury by thermal conductivity using gold film/thin film/UV detectors of Jerome instrument; no information regarding digestion/extraction.
    TT_FuseIron trioxide by titration after fusion, decomposition and precipitation.
    TT_HClCarbonate carbon and carbon dioxide (acid soluble carbon) by coulometric titration after HClO4 digestion and extraction.
    VOLCarbon dioxide or carbonate carbon by evolution after acid decomposition; aka ""gasometric"" or ""manometric"".
    WDX_FuseMajor and minor elements by wavelength-dispersive X-ray fluorescence spectrometry after LiBO2 fusion digestion.
    WDX_RawChlorine, iodine and bromine by wavelength-dispersive X-ray fluorescence spectrometry on raw sample.
    parameter
    Parameter.

    The suggested field name for a Species_Unit_Method column in crosstabbed chemistry tables. These field names concatenate the Species and Unit fields, and includes the general analytical method (first part of the amethod field). Textual values of no more than 32 characters. (Source: this data release) Concatenation of species, unit, and the characters of the amethod field to the left of the first underscore.
    tblname
    Table name.

    Textual values of no more than 16 characters. (Source: this data release)
    ValueDefinition
    Chem_ESChemical analyses by emission spectroscopy
    Chem_ICPAESChemical analyses by inductively-coupled plasma atomic emission spectroscopy
    Chem_ICPMSChemical analyses by inductively-coupled plasma mass spectroscopy
    Chem_NAAChemical analyses by neutron activation analysis
    Chem_OtherChemical analyses of "totally" digested samples by methods other than those identified by other values of this field.
    Chem_XRFChemical analyses by either energy dispersive or wavelength dispersive X-ray fluorescence
    Partial_A2ZChemical analyses of partially digested samples using HCl with H2O2, KI, or both
    Partial_AqRegChemical analyses of partially digested samples using aqua regia
    Partial_OtherChemical analyses of partially digested samples using other digestion procedures
    bestvalue
    Best analytic value for each element obtained by selecting the most reliable analytic methods from among those that were performed on the sample (Source: USGS)
    rec_id
    Record ID.

    Integer values. Integer of width 8. (Source: this data release)
    Range of values
    Minimum:1
    Maximum:10567162
    Resolution:1
    lab_id
    Lab ID.

    Unique identifier assigned to each submitted sample by the Sample Control Officer of the analytical laboratory that received the sample. Textual values of no more than 10 characters. (Source: this data release) Alphanumeric identifiers without intrinsic scientific significance
    species
    Chemical species.

    Element, oxide, compound, or property that was determined or measured by the laboratory. Textual values of no more than 8 characters. (Source: this data release)
    ValueDefinition
    LiLithium
    BeBeryllium
    BBoron
    C_totCarbon (total)
    C_orgCarbon (organic)
    C_crbCarbon (carbonate)
    CO2Carbon dioxide
    NNitrogen
    FFluorine
    NaSodium
    MgMagnesium
    AlAluminum
    SiSilicon
    PPhosphorus
    SSulfur
    ClChlorine
    KPotassium
    CaCalcium
    ScScandium
    TiTitanium
    VVanadium
    CrChromium
    MnManganese
    FeIron
    CoCobalt
    NiNickel
    CuCopper
    ZnZinc
    GaGallium
    GeGermanium
    AsArsenic
    SeSelenium
    BrBromine
    RbRubidium
    SrStrontium
    YYttrium
    ZrZirconium
    NbNiobium
    MoMolybdenum
    RuRuthenium
    RhRhodium
    PdPalladium
    AgSilver
    CdCadmium
    InIndium
    SnTin
    SbAntimony
    TeTellurium
    IIodine
    CsCesium
    BaBarium
    LaLanthanum
    CeCerium
    PrPraseodymium
    NdNeodymium
    SmSamarium
    EuEuropium
    GdGadolinium
    TbTerbium
    DyDysprosium
    HoHolmium
    ErErbium
    TmThulium
    YbYtterbium
    LuLutetium
    HfHafnium
    TaTantalum
    WTungsten
    ReRhenium
    OsOsmium
    IrIridium
    PtPlatinum
    AuGold
    HgMercury
    TlThallium
    PbLead
    BiBismuth
    PoPolonium
    ThThorium
    UUranium
    SplWtAuWeight of sample used for gold analysis
    SplWtFAWeight of sample used for fire assay analysis
    unit
    Units of measure.

    Unit of measurement associated with the accompanying concentration value. Textual values of no more than 8 characters. (Source: this data release)
    ValueDefinition
    ggrams
    pctpercent by weight
    ppmparts per million by weight
    qvalue
    Qualified value.

    Qualified concentration value for the associated Species and reported in the associated Unit. Values less than the lower limit of determination are negative while values greater than the upper limit of determination have a .1111 suffix. Real numbers stored in double precision. (Source: this data release)
    Range of values
    Minimum:-200000
    Maximum:584300
    amethod
    Analytical method.

    Analytical method code (abbreviation) for the method used to determine the associated Species. Textual values of no more than 32 characters. (Source: this data release)
    ValueDefinition
    AA_CVMercury by cold-vapor atomic absorption spectrometry after multi-acid digestion and solution.
    AA_CV_WOMercury by wet oxidation and cold-vapor atomic absorption spectrometry ("flameless"); HNO3-H2SO4-HClO4 digestion, Hg aerated to silver screen, amalgamator heated in furnace, Hg vapor measured in AAS.
    AA_FESodium and potassium by flame emission spectrometry (flame photometry) after HF-HClO4 dissolution or LiBO2 fusion.
    AA_F_AZ_Fuse_PSilver, arsenic, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by flame atomic absorption spectrometry after partial digestion by K2S2O7 fusion, HCl-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_AZ_H2O2_PSilver, arsenic, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by flame atomic absorption spectrometry after partial digestion with HCl-H2O2-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_AZ_HCl_PSilver, arsenic, bismuth, cadmium, antimony and zinc by flame atomic absorption spectrometry after partial digestion by HCl-KI, ascorbic acid and selective organic extraction with Aliquat 336-MIBK.
    AA_F_FuseMajor and minor elements by flame atomic absorption spectrometry after LiBO2/Li2B4O7 fusion digestion.
    AA_F_Fuse_PMolybdenum and antimony by flame atomic absorption spectrometry after K2S2O7 (Mo) or NH4I (Sb) fusion, partial acid digestion, and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HBrGold and tellurium by flame atomic absorption spectrometry after HBr-Br2 digestion and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HCl_OE_PAntimony by flame atomic absorption spectrometry after NH4I fusion, digestion with HCl, and selective organic extraction with Aliquat 336-MIBK.
    AA_F_HFMajor and minor elements by flame atomic absorption spectrometry after multi-acid digestion with HF.
    AA_F_HNO3_PSilver, bismuth, cadmium, cobalt, copper, nickel, lead and zinc by flame atomic absorption spectrometry after partial digestion with hot HNO3.
    AA_GF_HBrGold and tellurium by graphite furnace atomic absorption spectrometry after HBr-Br2 digestion and selective organic extraction with Aliquat 336-MIBK.
    AA_GF_HFArsenic, gold, bismuth, indium, antimony, tellurium and thallium by graphite furnace atomic absorption spectrometry after multi-acid digestion with HF and selective organic extraction with Aliquat 336-MIBK.
    AA_GF_STThallium by graphite furnace atomic absorption spectrometry after Na2O2 sinter, HCl-HNO3 dissolution, and selective organic extraction with DIBK.
    AA_HG_AcidSelenium by flow injection or continuous flow hydride generation-atomic absorption spectrometry after digestion with HNO3-HCl-H2SO4-KMnO4.
    AA_HG_HFArsenic, antimony, selenium and tellurium by flow injection or continuous flow hydride generation-atomic absorption spectrometry after multi-acid digestion with HF.
    AA_HG_STArsenic and antimony by flow injection or continuous flow hydride generation-atomic absorption spectrometry after Na2O2 sinter digestion.
    AA_TRMercury by thermal release and atomic absorption spectrometry after heating (Vaughn-McCarthy method).
    AA_TR_WMercury by thermal release and atomic absorption spectrometry after heating (Vaughn-McCarthy method) and use of a willemite screen.
    AES_AR_PMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after partial digestion with aqua regia.
    AES_AZ_PSilver, arsenic, gold, bismuth, cadmium, copper, molybdenum, lead, antimony and zinc by inductively coupled plasma-atomic emission spectrometry after partial digestion with HCl-H2O2.
    AES_Acid_PMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after unknown partial acid digestion.
    AES_FuseMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after Li2B4O7 fusion digestion.
    AES_HFMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after digestion with HF-HCl-HNO3-HClO4.
    AES_HF_REERare earth elements by ion exchange and inductively coupled plasma-atomic emission quantitative spectrometry after HF-HCl-HNO3-HClO4 digestion.
    AES_IEMolybdenum, niobium and tungsten by inductively coupled plasma-atomic emission quantitative spectrometry after HF-HCl-HNO3-HClO4 digestion and ion exchange separation.
    AES_STMajor and minor elements by inductively coupled plasma-atomic emission spectrometry after Na2O2 sinter digestion.
    CB_CHNCarbon, hydrogen and nitrogen by gas chromatography/thermal conductivity (CHN elemental) analyzer after combustion.
    CB_IRCCarbon and sulfur by infrared detection after combustion.
    CB_TCTotal carbon and organic carbon by thermal conductivity detection after combustion.
    CB_TTSulfur by iodometric titration after combustion.
    CM_AcidBromine by colorimetry after acid digestion.
    CM_Acid_PArsenic by modified Gutzeit apparatus confined-spot method colorimetry after partial digestion in KOH-HCl and chemical separation.
    CM_FuseMajor and minor elements by colorimetric spectrophotometry after fusion digestion.
    CM_Fuse_PMolybdenum and antimony by colorimetry after partial digestion by K2S2O7 fusion (Mo) or NaHSO4 fusion-HCl digestion (Sb, rhodamine B).
    CM_HFMajor and minor elements by colorimetric spectrophotometry after multi-acid digestion with HF.
    CM_HNO3_PCopper, lead and zinc by colorimetry after partial digestion with HNO3.
    CM_HSFFluorine by chemical separation and colorimetric spectrophotometry; chemical separation to fluorosilicic acid (H2SiF6), converted to silicomolybdate, reduced to Mo blue.
    CM_PC_PUranium by paper chromatography after partial digestion with HNO3.
    CM_SDDCArsenic by colorimetric spectrophotometry after digestion in HF-aqua regia and chemical separation with SDDC.
    CM_STChloride by colorimetric spectrophotometry after Na2CO3 and ZnO sinter digestion.
    CM_ST_PTungsten by colorimetry after partial digestion with carbonate sinter.
    CPOrganic carbon, carbonate carbon and totals by computation.
    DNUranium and thorium by delayed neutron activation counting.
    EDXMinor elements by energy-dispersive X-ray fluorescence spectrometry.
    ES_QMajor and minor elements by quantitative emission spectrography.
    ES_SQMajor and minor elements by semi-quantitative emission spectrography.
    FA_AAGold, silver and platinum group elements by graphite furnace atomic absorption spectrometry after PbO fire assay chemical separation.
    FA_DCGold by direct current plasma-atomic emission spectroscopy or atomic absorption spectrophotometry after PbO fire assay chemical separation.
    FA_ESGold and platinum group elements by direct-current arc quantitative emission spectrography after PbO fire assay chemical separation.
    FA_MSPlatinum group elements by inductively coupled plasma-mass spectrometry after NiS fire assay chemical separation.
    FL_Acid_PSelenium by acid digestion and fluorometry; HNO3 digestion, H2O2 added, HClO4 digestion, HCl reduced, reacted with 2,3-diaminonapthalene.
    FL_HFBeryllium, tin and uranium by fluorometry after multi-acid digestion with HF.
    FL_HNO3Selenium by fluorometry after digestion with HNO3-H3PO4.
    GVDensity, moisture and weight by gravimetry; ash or loss on ignition by weight loss after heating at 900 degrees C.
    GV_WOOrganic carbon, as CO2, by wet oxidation and gravimetry; H2SO4 digestion, oxidized with CrO3-H2SO4, CO2 collected on ascarite; data from "Energy Group SP Open File UGR-068".
    ISE_FuseChloride, fluoride and iodide by ion specific electrode after fusion digestion.
    ISE_HFChloride by ion specific electrode after multi-acid digestion with HF.
    MS_AR_PMajor and minor elements by inductively coupled plasma-mass spectrometry after partial digestion with aqua regia.
    MS_HFMajor and minor elements by inductively coupled plasma-mass spectrometry after HF-HCl-HNO3-HClO4 digestion.
    MS_STMajor and minor elements by inductively coupled plasma-mass spectrometry after Na2O2 sinter digestion.
    MS_ST_REERare earth elements by inductively coupled plasma-mass spectrometry after Na2O2 sinter digestion.
    NA_LCMajor and trace elements by long count instrumental neutron activation analysis; no digestion/extraction necessary.
    NA_SCMajor and trace elements by short (abbreviated) count instrumental neutron activation analysis; no digestion/extraction necessary.
    TC_JrmMercury by thermal conductivity using gold film/thin film/UV detectors of Jerome instrument; no information regarding digestion/extraction.
    TT_FuseIron trioxide by titration after fusion, decomposition and precipitation.
    TT_HClCarbonate carbon and carbon dioxide (acid soluble carbon) by coulometric titration after HClO4 digestion and extraction.
    VOLCarbon dioxide or carbonate carbon by evolution after acid decomposition; aka ""gasometric"" or ""manometric"".
    WDX_FuseMajor and minor elements by wavelength-dispersive X-ray fluorescence spectrometry after LiBO2 fusion digestion.
    WDX_RawChlorine, iodine and bromine by wavelength-dispersive X-ray fluorescence spectrometry on raw sample.
    summary
    Related analyses.

    Summary of all analyses for the total concentration of a single element in a samples; analyses are listed in order of 'Best Value'. Used only in the bestvalue table. Textual values of no more than 256 characters. (Source: this data release) List of the values of concentration and analytical method drawn from fields of the chemistry table where lab_id and chemical species matches the row.
    parameter
    Parameter.

    The suggested field name for a Species_Unit column in crosstabbed chemistry tables. These field names concatenate the Species and Unit fields. Textual values of no more than 32 characters. (Source: this data release) Concatenation of chemical species and unit fields, separated by underscore
    mthd_parameter
    Method parameter.

    The suggested field name for an AMethod column in crosstabbed chemistry tables. Textual values of no more than 32 characters. (Source: this data release) Concatenation of chemical species field value and "_Mthd"

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Steven M Smith
    Southwest Region
    Geologist
    U.S. Geological Survey
    Box 25046 Mail Stop 973
    Denver Federal Center
    Denver, CO
    USA

    303-236-1192 (voice)
    303-236-3200 (FAX)
    smsmith@usgs.gov

Why was the data set created?

The National Geochemical Database is a curated repository intended to contain all geochemical analyses carried out by and for geological studies conducted by the U.S. Geological Survey. Sample characteristics, including the location from which the sample was taken, and characteristics of the location and nearby geographic area, are included as well as analytical determinations of the concentration of elements and other chemical species. The work of USGS is strongly concentrated in earth sciences, so most of the analyses are of inorganic components. Likewise as a US Federal government organization, the work of USGS focuses on areas governed by the United States. Samples are located throughout the world, but most of the samples come from the US.

How was the data set created?

  1. From what previous works were the data drawn?
    PLUTO (source 1 of 2)
    U.S. Geological Survey, 2001, Geochemistry of unconsolidated sediments in the US from the PLUTO database: U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    Baedecker, Philip A., Grossman, Jeffrey N., and Buttleman, Kim P., 1998, National Geochemical data base: PLUTO geochemical data base for the United States: U.S. Geological Survey Digital Data Series DDS-47.

    Online Links:

    Type_of_Source_Media: Digital and paper
    Source_Contribution: Sediment analyses from PLUTO were consolidated into the NGDB
    RASS (source 2 of 2)
    U.S. Geological Survey, 2001, Geochemistry of unconsolidated sediments in the US from the RASS database: U.S. Geological Survey, Reston, VA.

    Online Links:

    Type_of_Source_Media: Digital files and paper records
    Source_Contribution:
    Sediment geochemical analyses from the RASS database were combined into NGDB
  2. How were the data generated, processed, and modified?
    Date: 2016 (process 1 of 2)
    Chemical analyses were carried out by USGS laboratories or by other organizations contracted by USGS to carry out those analyses, over a period of decades; these results begin in the 1960s and continue to this day.

    Much of the data now in the NGDB had been previously compiled into other collections such as PLUTO and RASS. Those older databases are now subsumed into the NGDB and the sediment sample analyses they contained are represented here.

    This process occurred over many decades, and the current compilation has reached maturity in 2016.
    Date: 2016 (process 2 of 2)
    The Best Value data set is a subset of data that represents one "best value" per species for each of its samples.

    This data set was created by ranking analytical methods, taking into account factors which vary between methods. These include weight of sample analyzed, method of decomposition of the sample during the preparation for analysis, sensitivity and accuracy of the instrument used in each method, upper and lower limits of detection for a given element by a given method, the age of the method and stage of its development when a specific analysis was performed, and the exact analytical laboratory and equipment used. The dataset was populated, species by species, first with detected values, from the highest ranked analytical method to the lowest, and then with non-detect values, from the lowest to the highest. Each "best value" per species per sample has a value, an analytical method code for that value, and a summary of one or more possible values from which the "best value" was derived.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
    Uncertainty of the point locations is exprssed, where this could be determined, in the field coord_prec_est. The information provided there accounts for the common and officially accepted practice, in years past, of specifying sampling locations by the southeast corner of the map quadrangle from which the sample was taken, and other indications that the original coordinates were expressed with limited precision. Yes, we know that accuracy and precision are not the same thing.
  3. How accurate are the heights or depths?
    Sample depth is given as reported by the original investigator, and the compiler had no independent way to check those values.
  4. Where are the gaps in the data? What is missing?
    In general, chemical analyses were carried out to pursue specific scientific objectives of a research project. Consequently there are no samples for which results were determined for every possible chemical analysis described in this database. Some analyses were rarely performed, and some were commonly performed. The table below shows, of the 335,026 samples, how many include an analysis, by any method, of each chemical species, with the proportion of samples (expressed as percent) for which an analysis of that chemical species was reported.

      Species  Samples Percent analyzed
    ------------------------------------
           Ag   306098 91.0%
           Al   103967 31.0%
           As   301766 90.0%
           Au   291781 87.0%
            B   220731 65.0%
           Ba   295186 88.0%
           Be   297407 88.0%
           Bi   297086 88.0%
           Br     1148  0.0%
           Ca   293580 87.0%
        C_crb    10426  3.0%
           Cd   299208 89.0%
           Ce   100061 29.0%
           Cl      959  0.0%
           Co   297568 88.0%
          CO2     4131  1.0%
        C_org    10301  3.0%
           Cr   299159 89.0%
           Cs    12259  3.0%
        C_tot    12747  3.0%
           Cu   307410 91.0%
           Dy     7084  2.0%
           Er     7077  2.0%
           Eu    83649 24.0%
            F     6708  2.0%
           Fe   296605 88.0%
           Ga   111971 33.0%
           Gd     7112  2.0%
           Ge    35116 10.0%
           Hf    15267  4.0%
           Hg    96627 28.0%
           Ho    79251 23.0%
            I      295  0.0%
           In    14886  4.0%
           Ir     6533  1.0%
            K    96251 28.0%
           La   291475 87.0%
           Li   101599 30.0%
           Lu    10655  3.0%
           Mg   293871 87.0%
           Mn   298943 89.0%
           Mo   299589 89.0%
            N      883  0.0%
           Na   120052 35.0%
           Nb   290420 86.0%
           Nd    82287 24.0%
           Ni   299184 89.0%
           Os     5480  1.0%
            P   121758 36.0%
           Pb   308204 91.0%
           Pd    17637  5.0%
           Pr     9508  2.0%
           Pt    16870  5.0%
           Rb    13198  3.0%
           Re    12660  3.0%
           Rh     6128  1.0%
           Ru     6119  1.0%
            S    11998  3.0%
           Sb   257566 76.0%
           Sc   288005 85.0%
           Se    51644 15.0%
           Si    19378  5.0%
           Sm    13820  4.0%
           Sn   292452 87.0%
      SplWtAu    10349  3.0%
      SplWtFA      240  0.0%
           Sr   292511 87.0%
           Ta    87913 26.0%
           Tb    11774  3.0%
           Te    21229  6.0%
           Th   215034 64.0%
           Ti   295109 88.0%
           Tl    30514  9.0%
           Tm     6646  1.0%
            U   113994 34.0%
            V   302037 90.0%
            W   233285 69.0%
            Y   297188 88.0%
           Yb    84369 25.0%
           Zn   314115 93.0%
           Zr   218529 65.0%
    
  5. How consistent are the relationships among the observations, including topology?
    The samples described in the database were collected by a wide variety of researchers over a long period of time, and the analyses conducted on those samples were carried out for varying purposes. In addition, the sample preparation and analytical methodology varied through time as the technology available changed. The result is that samples may not be directly comparable due to differences in sampling procedure, preparation, analytical instrumentation, or choice of chemical species to analyze.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints: none
  1. Who distributes the data set? (Distributor 1 of 1)
    Peter N Schweitzer
    USGS ER GD
    Geologist
    12201 Sunrise Valley Drive
    Reston, VA
    USA

    703-648-6533 (voice)
    703-648-6252 (FAX)
    pschweitzer@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    This database has been approved for release by the U.S. Geological Survey (USGS). Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the database is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 07-Dec-2016
Metadata author:
Schweitzer, Peter, N
Eastern Mineral Resources Team
12201 Sunrise Valley Drive Mail Stop 954
Reston, VA
USA

703-648-6533 (voice)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://mrdata.usgs.gov/metadata/ngdbsed.faq.html>
Generated by mp version 2.9.47 on Mon Mar 26 17:20:49 2018