Lithium Deposits in the United States

The Esri ArcGIS 10.7 geodatabase contains 1 point and 2 polygon feature classes, 8 attribute tables, and 15 relationship classes. Relationship classes link tables using the Ftr_ID or Site_ID fields. Feature classes are also provided as Esri shapefiles; attribute tables are provided as Excel and comma-separated values (CSV) files. The description of each database layer (feature class) and attribute table is provided below, followed by general information about concepts and terms used in the development of the database.

DATABASE LAYERS AND TABLES

The Loc_Pt feature class contains point locations of mines, mineral occurrences (deposits and prospects), and mineral regions, and the attribute information describing the location, source report, scale of the map used to obtain the location, and if the location has a polygonal footprint in the Loc_Poly feature class. In the database, all features have a point location, except for surface workings.

The Loc_Poly feature class contains footprints or polygons of deposits, geothermal reservoirs, mineral districts, and mining districts. If a source report shows a location as a polygon, the polygon is digitized, and the approximate centroid of the polygon is added to the Loc_Pt layer. Attribute information about the location is provided in the Loc_Pt layer. Mines are represented as points in the database, even when footprints are presented in source reports. Where possible, the approximate extent of the mining operation area, determined from imagery, is presented in the surface workings layer (see Loc_Poly_Sw).

The Loc_Poly_Sw feature class contains the approximate area of mining-related activity, or “surface workings” as shown on Esri imagery. These polygonal outlines have no corresponding point location in the database, nor do they have links to other tables. The attribute information for surface workings contains the date of the imagery and basic location information including state and county names. Surface workings must be at least 1,000 feet (300 meters) in one dimension to be digitized, and multiple workings that are 500 feet (150 meters) or less apart are combined into one outline. No attempt is made to distinguish between the types of surface workings (for example, roads, pits, leach pads, waste piles, etc.), even when presented in source reports.

The Site table is used to identify related features, such as a deposit and the mine(s) operating on it, or a mine and its related deposits. Each site has a unique identification value in the Site_ID field. The Site_ID is used in all tables except the References table. The Site table also indicates where information about a site occurs within the database. For example, if the Resources field in the Site table contains the value “Yes”, resource information is available in the Resources table.

The GeolMinOcc table contains information about the geology of mineral deposits and prospects. Every attempt was made to compile information as reported in the source report. For example, if one source report states the valuable material as “spodumene”, and another reports "lepidolite", the attribute field Value_Mat will contain all values. The value in the Ref_ID field is the primary source report for the record, for example, Kesler (1976). All information in the record comes from the primary source report unless an attribute field value contains a number in parentheses. This number denotes another source report whose Ref_ID is given in the Remarks field. Full citations for source reports are provided in the References table.

The Resources table contains reported resource and reserve information for mineral deposits. Initial (or earliest resource data found by USGS authors) and current resource data were compiled, even if information from intervening years was reported. Resource values were recorded as shown in source reports, including year reported, resource amount, units, and classification system(s). The definition of terms (for example, inferred, proven, probable, etc.) used in various resource classification systems may change through time. Resources extracted from older sources might not be compliant with current rules and guidelines in minerals industry standards such as National Instrument 43-101 (NI 43-101) or the Joint Ore Reserves Committee Code (JORC Code). Inclusion of material in the database is for descriptive purposes only and does not imply endorsement by the U.S. Government. If resources or reserves are reported for a group of features rather than an individual deposit, the Ftr_ID will show “-1111” and the resource or reserve is assigned to the “site” or Site_ID that groups those deposits in the Site table. The contained SI commodity amount (CntSIComAm) for the contained SI commodity (CntSICom) has been provided in one consistent unit (metric tons) for the user which is typically calculated value by USGS authors. A value ending with “111” as a decimal trailer indicates the value was calculated by USGS authors. Conversion factors used by USGS authors can be found on the USGS_Lithium_US_Merged_Excels file under the Conversions tab. For example, if a value in the Grade field is calculated by USGS authors to be 0.05 percent, then the value recorded in the database will be 0.05111. Where a range in values is provided for attribute fields such as Mat_Amnt, Grade, Contained, etc., the average of the range is reported within the field and the range of values is noted within the Remarks field. For consistency, resource values are converted to the International System of Units (SI units) by the USGS authors.

The Production table contains published production data for mines. Production is listed by commodity and reported as shown in the source reports. Reported production values are totaled by the USGS authors for the time period defined by the Year_From and Year_To values. If production is reported for a group of features, the Ftr_ID will show “-1111” and the production is assigned to the “site” or Site_ID that groups those mines in the Site table. The contained SI commodity amount (CntSIComAm) for the contained SI commodity (CntSICom) has been provided in one consistent unit (metric tons) for the user which is typically calculated value by USGS authors. A value ending with “111” as a decimal trailer indicates the value was calculated by USGS authors. Conversion factors used by USGS authors can be found on the USGS_Lithium_US_Merged_Excels file under the Conversions tab. For example, if a value in the Grade field is calculated by USGS authors to be 0.05 percent, then the value recorded in the database will be 0.05111. Where a range in values are provided for attribute fields such as Mat_Amnt, Grade, Contained, etc., the average of the range is reported within the field and the range of values are noted within the Remarks field. For consistency, production values are converted to the International System of Units (SI units) by the USGS authors.

The History table contains information derived from publicly available sources regarding the status of a mine, prospect, deposit, or mineral region through time. Values in the Status field indicate a condition or phase for the time period stated in the Year_From and Year_To fields. This information may not reflect the current status of a feature. For example, if the attribute record shows the status of a mine is “Active” and the Year_From and Year_To dates are 1936 and 1979, respectively, then the mine was active from 1936 to 1979; it is unknown if the mine is still active. The Last_Updt field shows the date that the record was last updated by the USGS authors.

The Dep_Model table contains mineral deposit model and geoenvironmental model classifications for deposits included in the database.

The Descr_Sum table contains relevant descriptions found in source reports. These descriptions are attributed according to the type of description, such as Geology, History, Production, Resources, etc. Descriptions pertain to individual features or to larger sites. The authors do not paraphrase or combine descriptions, and therefore, when a database feature is described in multiple reports, the feature will have multiple entries.

The References table contains the citation of the map or report(s) from which the point, polygon, or attribute information was obtained. The table also assigns a short reference, Ref_ID that is used throughout the database.

GENERAL INFORMATION

Mines are a man-made feature associated with the process of extracting, processing, or concentrating ore materials. In this database, mines have a point location, and where possible, the polygon boundary showing the extent of surface workings identified from imagery. No attempt is made to distinguish specific mine features like pits, dumps, tailings, etc. within the surface workings outline.

Mineral occurrences, defined as a concentration of a mineral considered potentially valuable, are attributed as deposits or prospects in the USGS Mineral Deposit Database (USMIN). Mineral deposits have a defined size and may have a grade indicated by current and (or) past production, and (or) a resource estimate. Prospects have sufficient data to describe at least two dimensions and has the presence of useful or valuable minerals or materials.

Mineral regions are attributed as geothermal reservoirs, mineral districts, or mining districts. Geothermal reservoirs are an underground storage of water trapped in porous rock capable of providing hydrothermal resources. Mineral districts are areas, usually designated by name, defined by a group of deposits of similar type, origin, and (or) commodity. Mining districts represent historic administrative areas organized by miners under the mining laws of the United States. Mining districts are typically an area containing a group of mines that exploited the same or related commodity. Mineral region polygons may overlap.

The locations of mine features, mineral occurrences, and mineral regions are commonly represented as points in source maps and reports, and occasionally as footprints (polygon outlines). In this database, all features have a point location, and some have an additional polygonal footprint. Surface workings in the Loc_Poly_Sw feature class are the exception—they do not have a corresponding point location or attribute information in the point layer. Otherwise, for points that have polygonal boundaries, the Loc_Pt feature class attribute field Loc_Poly contains the value “Yes” and the type of boundary is described in the Poly_Def field. For example, “Approximate extent of lithium lens on map”, “Extent of indicated mineral resource shown on map”, or “Mining district boundary”.

Each point and polygon feature is uniquely identified by a Ftr_ID. The Site_ID is used to indicate groups of related features, or “sites”. Tables are linked (related) using the Ftr_ID or the Site_ID fields. Some tables have more than one record describing a feature. For example, a point denoting a mine location may have many records in the Production table summarizing the dates and amounts of material produced. The database is designed to allow the user to navigate from the point or polygon layers to the linked table information or from the tables to the point and polygon layers.

All database information is derived from publicly available sources. The Last_Updt field shows the date that the record information was last updated by the authors. Full citations are listed in the References table, and each citation is assigned a short citation, Ref_ID that is used for identification in the database. With the exception of the Loc_Poly feature class the primary reference(s) is typically noted in the Ref_ID field. Additional references are enumerated after attribute field values, and the corresponding short reference is in the Remarks field. For example, the Commodity field shows “lithium; potassium (1); sodium (1); fluorine (1)”. This indicates the commodity “lithium” was derived from the primary reference denoted in the Ref_ID field as “Henry and others (2017)” and “potassium, sodium, and fluorine” were derived from a secondary reference denoted in the Remarks field as “(1) Rossi (2010)”.

There is no relevance to the order of data presented in lists. For example, if the Commodity field shows “lithium; boron; potassium”, that is the order in which those commodities were compiled by the authors and does not represent the order of importance. Additionally, in the GeolMinOcc table, lists in different fields do not relate. For example, if the Commodity field shows “lithium; boron; potassium”, the Value_Mat field may list related ore minerals in a different order. Similarly, the data lists reflect the order in which the information was compiled. Fields with lists are present in the Site, Loc_Pt, and GeolMinOcc tables.

Field or attribute records that contain "Null" values in the file geodatabase, were checked for available data, and no data were found. In some cases, an entire field may contain no information. These "Null" fields are maintained in the database structure for consistency with related USGS products and for possible future use if information becomes available.

Two points may occupy the same location. This occurs when there is a deposit with a mine, and the location of either the mine or the deposit is unknown. For example, a report provides a map showing the location of a deposit. The report also provides production data for underground “Mine X” that is mining the deposit but does not provide the location of “Mine X”. In this case, a second point representing “Mine X” is placed at the point location of the deposit.

Polygon features may overlap. Viewing polygons as outlines without color fills will show where polygon overlap occurs.

In the attribute section of this metadata, attribute fields from all feature classes and tables are listed in alphabetic order; corresponding feature classes and tables are listed in parentheses after the field name in the Attribute Label. For example, “Mat_Amnt (Production, Resources)” indicates the attribute field Mat_Amnt (material amount) occurs in the Production table and in the Resources table.