Anorthite
Description
A calcium-rich plagioclase feldspar mineral composed of calcium aluminosilicate. Anorthite occurs as brittle, translucent, white ,or gray crystals. It is found in many igneous rocks such as Gabbro and Granite. Major deposits occur in Italy (Trentino, the lavas of Vesuvius, and Monte Somma), Finland, Sweden (Södermanland), India (Tamil Nadu), Japan (Miyake), and the United States (New Jersey).
Synonyms and Related Terms
calcium feldspar; Anorthit (Deut.); anorthiet (Ned.); anortyt (Pol); anortita (Esp.); anortite (Port.); anortyt (Ned.)
Other Properties
Crystalline system = triclinic Cleavage = perfect in one direction Pleochroism = yellow to dark green to transparent to opaque
Luster = vitreous
| Composition | CaAl2Si2O8 |
|---|---|
| Mohs Hardness | 6.0-6.5 |
| Density | 2.74-2.76 |
| Refractive Index | 1.51 |
Authority
- Encyclopedia Britannica, http://www.britannica.com Comment: "anorthite" Encyclopædia Britannica [Accessed March 4, 2002].
- Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992
- Wikipedia, the free encyclopedia, at http://www.wikipedia.com Comment: http://en.wikipedia.org/wiki/Anorthite (accessed Jun 2005)
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=2.74-2.76