National Geochronological Database sample #3911

Outcrop or artificial surface exposure, Vein

Geographic location
-117.159722, 37.702778
117° 9' 35" W, 37° 42' 10" N
Nye county, NV
Goldfield 1:62,500 scale map quadrangle
Accurate to within 0.1 minute (~500 feet)
Source of sample Outcrop or artificial surface exposure
Rock name Vein
Description ALUNITE FROM VEIN AT TRUE DEPTH OF ABOUT 500 METERS; IN MILLTOWN ANDESITE
Laboratories USGS Menlo Park
Compiler name Nichols, S.L.
Date compiled 1978 04
Precision of location Accurate to within 0.1 minute (~500 feet)
Bibliographic reference Ashley, R.P., and Silberman, M.L., 1976, Direct Dating Of Mineralization At Goldfield, Nevada, By Potassium-Argon and Fission-Track Methods: Economic Geology, v. 71, p. 904-924.
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Geologic map unit -117.159722, 37.702778
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K-Ar age determinations

Age estimate 20.56 ± 0.4Ma
Type of analysis conventional K-Ar
6.35%, 6.35%, 6.26% K2O
Rock or mineral analyzed alunite
Analytical details
Lab sample ID CL-1828
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 6.32 %
Radiogenic 40Ar concentration 1.881
Radiogenic Ar 57 %
Comments AGE OF MINERALIZATION
Age estimate 20.41 ± 0.4Ma
Type of analysis conventional K-Ar
6.35%, 6.35%, 6.26% K2O; ARGON EXTRACTION SYSTEM NOT BAKED-OUT OVERNIGHT
Rock or mineral analyzed alunite
Analytical details
Lab sample ID CL-1828
Decay constants 4.72E-04, 0.585E-04, 1.19E-04*
K2O concentration 6.32 %
Radiogenic 40Ar concentration 1.868
Radiogenic Ar 61 %
Comments AGE OF MINERALIZATION