Strontianite is an uncommon strontium carbonate mineral that was sometimes encountered during fluorspar (fluorite) mining activities in the historic Cave-In-Rock mining district in Hardin County, Illinois. Although the last of the famous fluorspar mines in Cave-In-Rock closed in 1995, well crystallized specimens of strontianite can still occasionally be found at rock and mineral shows in the midwestern states. This is a fine example from the Minerva No. 1 mine in Cave-In-Rock. It consists of a large aggregate of radiating, snow-white, acicular crystals of strontianite with no matrix. Shown here under short wave UV, this specimen displays a similar bright blue/white fluorescent response under both short and long wave UV. This specimen measures 14 x 9 x 5 cm and weighs 293 grams.
The above photograph shows a large strontianite specimen from the Minerva No. 1 mine, Cave-In-Rock, Illinois, fluorescing bright blue/white under short wave UV (254nm). This specimen was mined by Ross Lillie in April 1990.
The same specimen shown under visible light.