Amphibole

Hornblende

Description

One of the major classes of silicate minerals. Amphiboles, in general, are a series of doubly hydrated silicates containing either Sodium, Calcium, Magnesium, Iron, or Aluminum. They are distinguished from pyroxenes, a second major class, by their cleavage planes. Amphiboles have cleavage angles of 56 and 124 degrees while pyroxenes have cleavage angles of 5 and 93 degrees. Amphiboles are commonly found in both Igneous and Metamorphic rocks. Examples of some amphibole minerals are: Hornblende, Glaucophane, amphibolite, actinolite, and Tremolite.

Synonyms and Related Terms

amfibol (Ces., Sven.); Amphibol (Deut.); amphibole (Fr.); amfibool (Ned.); amfibole (Pol.); anfíbola (Port.); (Sven.)

Density	2.9-3.2

Sources Checked for Data in Record

• R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997

• Wikipedia, the free encyclopedia, at http://www.wikipedia.com Comment: http://en.wikipedia.org/wiki/Amphibole (Accessed Mar. 20, 2006) -for non-English terms

• CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=2.9-3.2

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998