Anthophyllite
Encyclopedia : A : AN : ANT : Anthophyllite
| Anthophyllite | |
|---|---|
|
| |
| General | |
| Category | Mineral |
| Chemical formula | Hydrous Magnesium Iron silicate (Mg,Fe)7Si8O22(OH)2 |
| Identification | |
| Colour | gray to green, brown, and beige |
| Crystal system | orthorhombic; 2/m2/m2/m |
| Crystal habit | Rarely as distinct crystals. Commonly lamellar or fibrous. |
| Cleavage | perfect 55° |
| Mohs Scale hardness | 5.5 - 6 |
| Luster | Vitreous |
| Refractive index and Optical Properties | Optically (-) α=1.60 - 1.69 β=1.61 - 1.71 γ=1.62 - 1.72; 2V = 70° - 100° Indices increase with Fe content |
| Specific gravity | 2.85 - 3.2 |
| Diagnostic Features | Characterized by clove brown color, but unless in crystals, difficult to distinguish from other amphiboles without optical and/or X-ray tests. |
Anthophyllite is an amphibole mineral: (Mg, Fe)7Si8O22(OH)2, magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of anthophyllite are lamellar or fibrous and are used as asbestos. The name is derived from the Latin word anthophyllum, meaning clove, an allusion to the most common color of the mineral.
Occurrence
Anthophylite is the product of metamorphism of magnesium-rich rocks especially ultrabasic igneous rocks and impure dolomitic shales. It also forms as a retrograde product rimming relict orthopyroxenes and olivine, and as an accessory mineral in cordierite-bearing gneisses and schists. Anthophyllite also occurs as a retrograde metamorphic mineral derived from ultramafic rocks along with serpentine. Geographically, it occurs in Pennsylvania, southwestern New Hampshire, central Massachusetts, Franklin, North Carolina, and in the Gravelly Range and Tobacco Root Mountains of southwest Montana.References
- Klein, Cornelius., 2002, The Manual of Mineral Science, 22nd ed., John Wiley & Sons, Inc. ISBN 0-471-25177-1
- [Mindat]
- [Webmineral]
- [Mineral galleries]
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.