Siderophyllite
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| Siderophyllite | |
|---|---|
| General | |
| Category | Silicate mineral |
| Chemical formula | KFe++Al(Al2Si2)O10(F,OH)2 |
| Identification | |
| Color | Blue green, dark brown, black. |
| Crystal habit | Micaceous foliated |
| Crystal system | Monoclinic-Prismatic 2/m |
| Cleavage | Perfect basal |
| Fracture | Conchoidal |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous to dull |
| Streak | Greenish gray |
| Diaphaneity | Transparent to subopaque |
| Specific gravity | 3 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.582 nβ = 1.625 nγ = 1.625 |
| Birefringence | δ = 0.043 |
| References | [1][2][3] |
Siderophyllite is a rare member of the mica group of silicate minerals with formula KFe++Al(Al2Si2)O10(F,OH)2.
The mineral occurs in nepheline syenite pegmatites and granite and aplite greisens. It is associated with microcline and astrophyllite at Pikes Peak, Colorado. It is also found in the alkali pegmatites of Mont Saint-Hilaire, Quebec.
It was first described in 1880 for an occurrence near Pikes Peak, Colorado. The name derives from the Greek sideros, iron, and phyllon, leaf, in reference to its iron rich composition and perfect basal cleavage.
[edit] References
- ^ http://webmineral.com/data/Siderophyllite.shtml Webmineral
- ^ http://www.mindat.org/min-3651.html Mindat
- ^ http://rruff.geo.arizona.edu/doclib/hom/siderophyllite.pdf Mineral Handbook
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