Homestake Assays and Ore Reserve Records

Collection

Identifier: 5030

Staff Only

Scope and Contents

This collection includes the records of assays carried out by and for the Homestake Mining Company including assay sheets and ore estimates.

Series I Dry Drills consists of assay sheets for samples taken from dry drill holes.

Series II Assays consists of assays of ore from the South Dakota holdings of Homestake. These records include the assays for random grab pile and car samples as well as assays of systematically collected ore.

Series III Diamond Drill Assays consists of records of the core of rock recovered in long cylindrical sections by a diamond drill.

Series IV Reports consists of reports on ore estimates, correspondence, assay tabulation results, sketches and graphs prepared from the estimate information, reserve calculations, and annual reports from the Geologic Department and the Chief Geologist. Also found in this series are Life of Mine reports.

Dates

1895 - 2000
Majority of material found within 1940 - 1998

Creator

Homestake Mining Company (Organization)

Conditions Governing Access

This collection is housed at the Homestake Adams Research and Cultural Center with no restrictions to access. The collection may be utilized during normal operating hours or by appointment.

Biographical / Historical

Assaying is a laboratory procedure used to determine the metal content of ore samples. Assays are routinely utilized for exploration planning and estimating ore reserves by mining companies. The samples for assays are obtained from grab, channel, and drill sampling. Homestake Mining Company most often used channel sampling, a labor-intensive method until the mid-1920s, when samples from dry-drill and test hole sampling methods became preferred as they provided a deeper penetration of the ore body. From its inception in 1876 through the late 1920s, Homestake used the assay-ton system for assaying their mine samples. This system was developed in 1866 by Charles F. Chandler. By the late 1920s, most of Homestakes's bullion was sold to the U.S. Mint at a fixed gold price of $20.67 per troy ounce. To better ensure the profitability of the mine, Homestake decided to switch from the assay-ton system to a dollar-ton system.

Extent

53.25 Linear feet

Language of Materials

English

Additional Description

Abstract

The Homestake Assay and Ore Reserve Records consist of assay records, ore estimates, and reports. Materials from 1895 through 2000 are present in the collection with the bulk of the material dating from 1940 through 1998. The collection also contains graphs that were at one time, framed and matted by the Homestake Mining Company.

Arrangement

This collection has been arranged into four series. Documents originally housed in binders have been rehoused for preservation purposes but retain their original labels. Oversize items have been housed separately from the collection and are described by separation notes.

Series 1 Dry Drills have been arranged chronologically. See box list for more information.

Series 2 Assays have been arranged chronologically and thereunder by type of assay. Assays for specific areas such as Star Pillar and Maitland are found at the end of the series. See box list for more information.

Series 3 Diamond Drill Assays have been arranged numerically by drill hole number. See box list for more information.

Series 4 Reports have been arranged by type of document. Ore estimate reports are arranged by level. Please see box list for more information.

Related Materials

Additional archival materials related to the Homestake Assays and Ore Reserve Records can be found in the Homestake Mining Company Collection including the following: Homestake Map Collection, 5019 Homestake Survey Records, 5001 Homestake Mine Engineer Files, 5035 Homestake Geology Department Papers.