Benstonite on Fluorite

specimen number:
2013456

location:
Minerva Mine #1, Hardin Co., Illinois, USA

description:

Pale yellow waxy crystals of translucent benstonite measuring to 0.5 cm in size are scattered across the top of a beautiful grouping of golden yellow and gemmy blue fluorite crystals. The yellow crystals measure to 4.0 cm on edge. This is in very good condition. An attractive example for this rare species.

The Minerva No. 1 Mine, located in Hardin County, Illinois, was one of the major producers in the Illinois Kentucky Fluorspar District, a region well known for its fluorite deposits. Operated by the Minerva Oil Company, the mine was developed in the mid 20th century and consisted of extensive underground workings that followed mineralized veins through limestone host rock. The primary product was fluorite, which was mined for use in the steel and chemical industries, along with associated minerals such as calcite, galena, and sphalerite. The mine became one of the leading producers in the district during its years of operation, contributing significantly to domestic fluorspar supply before eventually closing as market conditions declined.

Benstonite is a rare barium calcium magnesium carbonate mineral that was first described from the Minerva No. 1 Mine, making it the type locality for the species. At this mine, benstonite occurs as colorless to pale crystals, often forming rhombohedral or blocky habits within cavities in the host rock. It is typically associated with fluorite, calcite, and other carbonate minerals formed in the hydrothermal environment of the deposit. The occurrence of benstonite at Minerva No. 1 is of particular interest because it represents a unique combination of elements under specific geochemical conditions. Specimens from this locality are highly valued by collectors due to the rarity of the mineral and its significance as a type species.

Questions about this specimen?
Send an email or call us: 314-341-1811.