| Description |
Historic geochemical samples from the DGGS, U.S. Geological Survey, and U.S. Bureau of Mines (USBM) archives were re-analyzed by DGGS using modern, quantitative, geochemical-analytical methods. Sample pulps were retrieved, examined, and split by DGGS staff into aliquots needed for the analyses. Splits of pulps were submitted to ALS Minerals Laboratories (ALS) for analysis. Where pulps were unavailable, coarse-reject material was prepped by ALS using the following method: coarse-reject samples were pulverized at ALS using flying disk or ring and puck style, low chrome, steel grinding mills. A sample split or total sample up to 250 g is pulverized, with 85 percent of the resulting material passing through a screen of 75 microns. Method PGM-ICP23: Pt, Pd, Au, 30-gram, FA-ICP-AES; Method: ME-MS81 38-element, fusion, ICP-MS; Method: ME-ICP61 33-element, 4-acid, ICP-AES; Samples with elements (Ag, Au, Cu, Pb, or Zn) above the detection limits in the analytical methods described above were re-analyzed using method: ME-OG62 Ore-grade elements, 4-acid, ICP-AES. Samples with gold (Au) above the detection limits in analytical method ME-OG62 were re-analyzed using method Au-GRAV21: Au, 30-g, FA |