Home » Minerals » Prehnite


Mineral Properties and Uses

Physical Properties of Prehnite

Chemical Classification silicate
Color white, green, gray, yellow
Streak white
Luster vitreous
Diaphaneity transparent to translucent
Cleavage basal
Mohs Hardness 6 to 6.5
Specific Gravity 2.8 to 3.0
Diagnostic Properties color, cleavage
Chemical Composition Ca2Al(AlSi3O10)(OH)2
Crystal System orthorhombic
Uses ornamental material, semiprecious gem

A cabochon of prehnite from Brazil. This gem is 3 carats, and approximately 10 millimeters by 8 millimeters.

Find it on Geology.com

More from Geology.com

Geologist Tools
Geologist Tools: Visit our store for a large selection of field and laboratory tools.
rock tumblers
Rock Tumblers - All about rock tumblers and rock tumbling. Read before you buy a tumbler.
Geology of Gems
Geology of Gems - The first comprehensive book on the geology of gem deposits.
US Diamond Mines
US Diamond Mines: Did you know that diamonds can be found in the United States?
Pictures of Opal: A collection of different types of opal from all around the world and Mars too!
Identifying Meteorites
Identifying Meteorites - Step one in identifying a possible meteorite is the magnet test.
Benitoite: A 1911 report on the discovery and geology of the State Gem of California.
Popigai Diamonds
The Largest Diamond Deposit in the world could be under Popigai Crater in Russia.

Prehnite beads
Beads of prehnite. Each bead is approximately 6 millimeter across.

More Minerals
  Mohs Hardness Scale
  Rock, Mineral and Fossil Collections.
  Geology Tools

© 2005-2016 Geology.com. All Rights Reserved.
Images, code, and content on this website are property of Geology.com and are protected by copyright law.
Geology.com does not grant permission for any use, republication, or redistribution.
Images, code and content owned by others are marked on the pages where they appear.