| Description |
Trace-element geochemical analyses were performed by ALS Chemex (ALS Minerals). All rock samples were crushed by ALS with a Terminator oscillating jaw crusher with chrome steel alloy plates so that at least 70 percent of the material passed through a -10 mesh (2 mm) screen. Representative aliquots of 250 grams and 30 grams each were taken using a stainless steel riffle splitter. These samples were then pulverized in a chrome steel ring mill so that 85 percent of the sample passed through a -200 mesh (75 micron) screen. All trace-element geochemical analyses and whole rock analyses were performed using representative splits of each 250-gram pulp, except gold, platinum, and palladium analyses, which were performed on a 30-gram representative split. All potentially mineralized samples were assayed for gold by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) following a 30-g fire assay fusion (FA), after four-acid, near-total digestion. Rock samples collected in 2008 and 2009 with the potential for elevated platinum-group-element content were assayed for gold, platinum, and palladium by 30-gram fire assay and inductively coupled plasma-mass spectrometry (ICP-MS) finish after four-acid, near-total digestion in 2008, and by 30-g fire assay and ICP-AES finish after four-acid, near-total digestion in 2009. All other trace-element geochemical analyses, from all years, were performed by ICP-AES methods after four-acid, near-total digestion. This method of digestion is possibly incomplete for some elements and may result in lower analytical results for these elements. To check reported trace-element geochemical assay values, DGGS inserts well-characterized standards in each laboratory batch throughout the sample order. Standards are checked by DGGS to make sure they fall within 2 standard deviations of accepted values, and if not, all samples in the batch are reanalyzed. |