Grossular

Description

A calcium aluminum garnet that occurs in shades of pale green, amber, pink, red, brown, or black. Yellow brown to red grossular, called hessonite, was used for ancient engraved gems and was mined in Ceylon. Green grossular, called gooseberry garnet, is found in Siberia. Grossular garnets are also found in the Urals, Italy, Switzerland, Mexico, and the United States (Maine and New Hampshire).

Synonyms and Related Terms

grossularite; hessonite; garnet; gooseberry garnet; grossulária (Port.)

Other Properties

Fracture = conchoidal. Luster = vitreous to resinous. Streak = colorless. Birefringence = none. Dispersion = 0.028 Pleochroism = none.

Fluorescence is pale orange in longwave UV and yellow in shortwave UV

Composition	Ca3Al2(SiO4)3
Mohs Hardness	7.0 - 7.5
Density	3.61
Refractive Index	1.734-1.740

Additional Information

Mineralogy Database: Grossularite

Authority

• Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982

• Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976

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

• C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979