Core of the Month: St. Joseph Minerals No. BN-1 Virgil Florence

Welcome back! We are reviving the KGS "Core of the Month" series, an online presentation of a rock core from our extensive collection at the Earth Analysis Research Library (EARL).

Core box from #BN-1 Virgil Florence core of Precambrian crystalline rocks
Portion of the St. Joseph Minerals #BN-1 core.

Call Number: C-1115
Operator: St Joseph Minerals
Farm Name: Florence, Virgil
Hole Number: BN-1
Purpose: Mineral Exploration

Taken from Bourbon County, this 3,082 foot core is exceptional because it showcases the entire sedimentary rock record of this area. Beginning with Upper/Middle Ordovician Lexington Limestone, the core continues into the crystalline basement rocks of the Precambrian age. Rock formations penetrated (from youngest to oldest) include the Ordovician Black River Formation, the Cambrian-Ordovician Knox Group, the Cambrian Mount Simon Formation, and Precambrian crystalline granite. This core offers a detailed look at the geology of Bourbon County and contributes to the knowledge of the subsurface in both the Bluegrass Region of Kentucky and the state.

Photograph of one box of the St. Joseph Minerals #BN-1 core.

Photograph of one box of the St. Joseph Minerals #BN-1 core containing the Precambrian crystalline rocks from the bottom of the borehole. The photo was produced as a part of a KGS initiative to photograph boxes of core from the collection at the KGS Earth Analysis Research Library.

The St. Joseph Minerals #BN-1 Virgil Florence borehole was drilled for mineral exploration. The Cambrian-Ordovician carbonate rock of the Knox Group in south-central Kentucky and middle Tennessee are host to Mississippi Valley-type ore deposits containing sphalerite, galena, and barite. The discovery of the Elmwood Zinc Deposit in 1967 spurred an increase in exploration in the United States for new sources of mineral ores (Anderson 1991). Mining companies such as St. Joseph Minerals, Exxon Minerals, Gulf Minerals, New Jersey Zinc, and Cominco American began a program of exploratory drilling in Ohio, Kentucky, and Tennessee to locate new mineral sources. Exploration in these states focused on the Cincinnati Arch where the target for these boreholes was the Mascot Dolomite, the top unit of the Cambrian-Ordovician Knox Group and a known producer of ores containing zinc and lead in middle and east Tennessee.

Cored intervals of the deeper formations of the No. BN-1 Virgil Florence.
Cored intervals of the deeper formations of the No. BN-1 Virgil Florence.

Because this core penetrates so many rock units, it can support research opportunities ranging from stratigraphic correlations and lithological work, theses and dissertations, to age dating, mineral investigations, and geochemistry. The rising importance of carbon sequestration and efforts to decrease carbon dioxide and methane emissions offer new possibilities for analysis of this core. The tools and techniques now available to geoscientists that did not exist when this hole was drilled justify revisiting No. BN-1 Virgil Florence.


Detailed core report with pictures for the No. BN-1 Florence.

Explore the geologic map at the location of the No. BN-1 Florence.

Reference Cited

This core is archived and available for examination at the KGS Earth Analysis Research Library, 2500 Research Park Drive, Lexington, KY 40511. Please call (859) 389-8810 to request materials and schedule a visit.

Text by Ray Daniels (KGS).

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Last Modified on 2023-01-05
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