ǝʇıuoʇ :: ƃuıɯɯnɔ

a metamorphic amphibole with the chemical composition (Mg,Fe)₇Si₈O₂₂(OH)₂, magnesium iron silicate hydroxide.

Monoclinic cummingtonite is compositionally similar and polymorphic with orthorhombic anthophyllite, which is a much more common form of magnesium-rich amphibole, the latter being metastable.

http://en.wikipedia.org/wiki/Cummingtonite

via digg