| Description |
Rock samples were 3 to 4 pounds. Pan concentrate samples were collected at sites that heavy minerals might accumulate. A heaping 14 inch gold pan of coarse gravel and sand was panned down to approximately 0.75 oz. Stream sediment samples were taken from the active portion of the stream bed. Approximately 8 oz. of silt and clay was collected. Placer concentrate samples consist of 0.1 cubic yards of stream bank material run through a sluice box and then panned down to produce 2.5 oz. of concentrate. Sluice concentrate samples were collected mostly from active placer mines. The samples consisted of 1 to 2 pounds of black sands and other heavy minerals left after the removal of placer gold by miners. The sample was then processed similar to the placer samples. Soil samples were collected from the C horizon with a hand auger. The pan concentrates and rock samples were dried and pulverized to a minus 150 mesh. The stream sediment and soil samples were dried and sieved to a minus 80 mesh.. Whole rock analysis for major and minor oxides was performed by fusing with a lithium borate flux to create a disk for X-ray fluorescence or further dissolved into solution for inductively coupled plasma. Rock, soil, and stream sediment samples were analyzed for a standard suite of 36 elements. Pan, placer, and sluice concentrates were also analyzed for platinum, palladiaum, and (when warranted) uranium, and thorium. Gold, platinum, and palladium were preconcentrated by fire assay with gold being followed by either an atomic absorption (AA) finish or ICP atomic emission spectrospcopy finish, and platinum and palladium followed by an ICP finish. Occasionally, a sample was analyzed for gold multiple times with erratic results and thus the lab reports the averaged result. The standard method for all elements (except mercury) was preparation with an aqua regia digestion and ICP atomic emission spectroscopy. The analysis for mercury was by aqua regia digestion followed by cold vapor measurement. When the upper limits of inductively coupled plasma or atomic absorption methods were exceeded for gold or silver the elements were re-analyzed by a fire assay preconcentration and a gravimetric finish. Elevated concentrations of antimony, bismuth, copper, iron, lead, and zinc were re-analyzed by multi acid digestion followed by atomic absorption low level assay. Samples of tin and tungsten that were below the detection limit of the inductively coupled plasma methods along with thorium, and uranium were analyzed by X-ray fluorescence. Some samples of barium by atomic absorption. |