Anthophyllite
A species of Minerals, Also known as Anthophylline, Gray Asbestos, Kupfferite Scientific name : Anthophyllite RockType : Minerals
Anthophyllite, A species of Minerals
Also known as:
Anthophylline, Gray Asbestos, Kupfferite
Scientific name: Anthophyllite
RockType: Minerals
Content
Description General Info
Description
Anthophyllite is an amphibole mineral: ☐Mg2Mg5Si8O22(OH)2 (☐ is for a vacancy, a point defect in the crystal structure), magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of anthophyllite are lamellar or fibrous and are classed as asbestos. The name is derived from the Latin word anthophyllum, meaning clove, an allusion to the most common color of the mineral. 
Physical Properties
Colors
White, greenish grey, green, clove brown, brownish green
Refractive Index
1.603-1.690
Pleochroism
Fe-rich - moderate: clove-brown, yellowish brown, grayish brown, brown-gray, brownish, clove-brown to dark brown, grayish blue to green, lilac
Optical Character
Biaxial positive or negative
Chemical Properties
Formula
◻{Mg2}{Mg5}(Si8O22)(OH)2
Elements listed
H, Mg, O, Si
Common Impurities
Ti,Al,Mn,Ca,Na
General Info
How to Select
Mineral samples displaying crystals of anthophyllite are considered rare, with aggregated pieces ideal for collections. A variety found in Butte, Montana displays a unique blue schiller effect and may be lightly pleochroic. Buyers may identify anthophyllite by its aggregated crystal habit and brown shades of color, while laboratory testing can confirm a sample through its grey streaking, and MOH hardness of 5.5 to 6.
Formation
Anthophyllite 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 serpentinite.
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