What is Calcite?
Calcite (CaCO3) is a very common and widespread mineral with many forms and colors. The properties that identify calcite are most prominently its relatively low Mohs hardness (3) and its high reactivity with even weak acids, such as vinegar, plus its prominent rhombohedral cleavage. Sometimes, in rare instances, the calcites are of extraordinary perfection and beauty.
What Happened in Schullsburg
Some of the world's finest calcites came out of Schullsburg Mines called the Calumet Mine and the Blackstone Mine.
Schullsburg is a quaint Wisconsin town located in the heart of the Upper Mississippi Valley lead-zinc district. As many as 125 mines, prospects and "diggins" are in the area. All of them are abandoned today. The last closed in the mid-1970's. Most digs have been reclaimed and traces of the former workings are hard to find. The Badger Mine Museum in Shullsburg preserves some of the heritage, and includes a model of the nearby Eagle-Picher mine.
What Makes the Schullsburg Calcites Great
The most desirable to collectors among the Schullsburg calcites are those that are complete-all-around and without damage. The famous Schullsburg form recognized all over the world is: a scalenohedron abundantly overgrown with lustrous 1 mm - 1.2 cm rhombohedral calcites in parallel stair-stepped growth, and, the central scalenohedron is capped by a transparent, gem quality, and lustrous, complex rhombohedral calcite crystal, which make for spectacular sceptered calcite specimens - some with striking phantoms.