Science Fair Project Encyclopedia
Prehnite
Prehnite is a phyllosilicate of calcium and aluminium with the formula: Ca2Al(AlSi3O10)(OH)2. Limited Fe3+ substitutes for aluminium in the structure. Prehnite crystallizes in the orthorhombic crystal system. It is brittle with an uneven fracture and a vitreous to pearly lustre. Its hardness is 6-6.5, its specific gravity is 2.80-2.90 and its color varies from light green to grey or white. It is translucent.
Though not a zeolite, it is found associated with them and with datolite , calcite, etc. in veins and cavities of basaltic rocks, sometimes in granites, syenites, or gneisses. It was first discovered in South Africa by Colonel Prehn, an early Dutch governor of the Cape of Good Hope colony.
Reference
- Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., ISBN 0471805807
See also
Last updated: 10-16-2005 00:56:10
10-26-2009 08:16:03
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details