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Refs

As

Au, Pd, Pt

C, S

ICP40

ICP16

ICP10

Hg

NAA

Sb

Se

Te, Tl

W

XRF

NURE

Analysis at USGS Laboratories of Major Elements by Wavelength-Dispersive X-ray Fluorescence Spectrometry

Method

Sample aliquants of 800 mg are ignited at 925°C for 45 minutes, and loss on ignition (LOI) is determined gravimetrically. Samples are then fused with lithium tetraborate at 1120°C. The resultant molten material is poured into a mold, yielding a homogeneous, optically flat glass disc for presentation to the x-ray spectrometer. Major elements (Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, MnO, and total Fe calculated as Fe2O3) are determined on the samples using wavelength dispersive x-ray fluorescence spectrometry using the method of Taggart and others (1981, 1987), Mee and others (1996), and Taggart and Siems (2002). Concentrations are determined using previously prepared calibration curves derived from a variety of international reference materials.

Reporting limits for major elements measured by XRF.

Element Units Lower limit Upper limit
SiO2 wt% 0.10 99.0
Al2O3 wt% 0.10 58.0
Fe2O3 wt% 0.04 28.0
MgO wt% 0.10 60.0
CaO wt% 0.02 60.0
Na2O wt% 0.15 30.0
K2O wt% 0.02 30.0
TiO2 wt% 0.02 10.0
P2O5 wt% 0.05 50.0
MnO wt% 0.01 15.0
LOI wt% 0.01 100.0

Data analysis

Distribution maps

Element
QA/QC
Conter-
minous
Alaska
Hawai`i
SiO2 (wt%) In progress no data no data
Al2O3 (wt%) In progress no data no data
Fe2O3 (wt%) In progress no data no data
MgO (wt%) In progress no data no data
CaO (wt%) In progress no data no data
Na2O (wt%) In progress no data no data
K2O (wt%) In progress no data no data
TiO2 (wt%) In progress no data no data
P2O5 (wt%) In progress no data no data
MnO (wt%) In progress no data no data
LOI (wt%) In progress no data no data