Pargasite
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| Pargasite | |
| General | |
|---|---|
| Category | Silicate mineral |
| Chemical formula | NaCa2(Mg,Fe++)4Al(Si6Al2)O22(OH)2 |
| Identification | |
| Color | Bluish green, grayish black, light brown |
| Crystal habit | Stout prismatic to tabular |
| Crystal system | Monoclinic; 2/m |
| Twinning | Simple and lamellar - common |
| Cleavage | {110} perfect |
| Fracture | Splintery |
| Mohs Scale hardness | 5 - 6 |
| Luster | Vitreous |
| Diaphaneity | Translucent, will transmit light on thin edges. |
| Specific gravity | 3.04 - 3.17 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.630 nβ = 1.640 nγ = 1.650 |
| Birefringence | δ = 0.020 max. |
| References | [1][2][3] |
Pargasite is a complex inosilicate mineral with formula NaCa2(Mg,Fe++)4Al(Si6Al2)O22(OH)2.
It was first described for an occurrence in Pargas, Finland in 1814 and named for the locality.[3]
It occurs in high temperature regional metamorphic rocks and in the skarns within contact aureoles around igneous intrusions. It also occurs in andesite volcanic rocks and altered ultramafic rocks.[1]
[edit] References
- ^ a b http://www.handbookofmineralogy.org/pdfs/pargasite.pdf Handbook of Mineralogy
- ^ http://www.mindat.org/min-3119.html Mindat
- ^ a b http://webmineral.com/data/Pargasite.shtml Webmineral
