Not a Mica, nor a phyllosilicate. Anthophyllite is a inosilicate - 2D infinite chains of silicate tetrahedra, which, morphologically resemble a phyllosilicate network. Anthophyllite occurs as bladed aggregates, much like this specimen, and on a smaller scale shows lamellar with elastic fibers and easy to mistake for a mica mineral.
Typically found in medium to high grade metamorphic amphibolites and gneisses. Associated with talc, chlorite, and micas. (Handbook of Mineralogy).
This specimen is a tight aggregate as that described above.
Anthophyllite
Formula
[box]Mg7Si8O22(OH)2
Crystal System
Orthorhombic
Crystal Habit
Fibrous, Lamellar, Massive
Cleavage
Perfect, Distinct, Distinct
Luster
Vitreous - Pearly
Color
white, greenish gray, green, clove brown, brownish green