Anhydrite

From Ohio History Central

The name anhydrite comes from two Greek words meaning "without water." In fact, anhydrite is very "dry" and it easily takes up water. When it absorbs water it changes to gypsum, a much more common mineral in Ohio. And in nature anhydrite forms when gypsum looses its water. This mineral is used in the production of the industrial chemical sulfuric acid, and in the production of paper.

Facts

Chemical Composition:Calcium sulfate (CaSO4)
Mineral class:Sulfates
Crystallization:Orthorhombic
Crystal habit:Commonly massive or granular ; tabular crystals uncommon.
Specific gravity:2.9 - 3.0
Hardness:3 1/2
Color:colorless when pure; often colored with impurities. Color in Ohio: usually gray or blue
Transparency:Transparent to translucent
Luster:Vitreous if well crystallized, greasy if massive.
Streak:white
Occurence:<img width="195" height="172" title="Map of anhydrite occurence" alt="Map of anhydrite occurence" src="images/naturalHistory/minerals/anhydritemap.gif" />

Anhydrite occurs in Europe and North America. In Ohio, anhydrite is found in open stone excavations and underground mines in the northern part of the state. It occurs in massive beds or nodules along with dolomite or halite, and has been recorded in three counties.In northern Ohio massive beds or nodules of anhydrite occur with dolomite or halite in deeper quarry workings and mines.

Resources

  • Sorrell, Charles A. Rocks and Minerals; Golden Press, New York, NY; 1973.
  • Pough, Frederick H. A Field Guide to Rocks and Minerals; Houghton Mifflin, Boston, MA; 1976.
  • Carlson, Ernest H., ed. Minerals of Ohio; Ohio Division of Geological Survey, Columbus, OH; Bulletin 69; 1991.

See Also