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Drilling and Sampling Tertiary Gold-Bearing Gravels At Badger Hill, Nevada County, California.

Authors
McLellan-RR; Berkenkotter-RD; Wilmot-RC; Stahl-RL
Source
NTIS: PB 240 020 :50 pages
Link
NIOSHTIC No.
10009286
Abstract
As part of an effort to develop new or improved placer mining technology in the Tertiary gold-bearing channel gravel of northern California, the Bureau of Mines conducted investigations at the old Badger Hill placer mine in Nevada County, California, to collect data and information regarding drilling and sampling methods and deposit characteristics. Sampling studies involved the collection and processing of 400 tons of large- and small-volume samples from drill holes, underground workings, surface pits, and blasthole rounds. A total of 355 samples averaging 2,296 pounds per sample provided reasonably accurate data for analysis of the gold distribution. These studies indicated that the bulk of the gold is within 40 feet of bedrock in stacked, lenticular zones of cemented gravel that are largely confined to the relatively narrow, meandering course of the deepest portion of the bedrock channel. Drilling studies involved the testing of truck-mounted rotary, bucket, and vibratory drills, none of which proved to be a completely versatile tool for sampling quickly and reliably both consolidated and unconsolidated gravel.
Publication Date
19740101
Document Type
IH; Report of Investigations
Fiscal Year
1974
NTIS Accession No.
PB-240020
NTIS Price
A04
Identifying No.
RI 7935
NIOSH Division
DRC;
Source Name
NTIS: PB 240 020
State
CA; NV;
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