Actinolite

܆Ca₂(Mg_4.5-_2.5Fe₂+_0.5-_2.5)Si₈O₂₂(OH)₂IMA symbol: Actredefined

Actinolite is a silicate mineral with the formula ܆Ca2(Mg4.5-2.5Fe2+0.5-2.5)Si8O22(OH)2, crystallizing in the monoclinic system. It has a calculated density of 3.117 g/cm3. Its streak is white.

Photos

Crystallography

Crystal system	monoclinic crystal systemWikidata (CC0)
Space group	C 1 2/m 1
Cell (Å, °)	a = 9.866, b = 18.098, c = 5.284; α = 90, β = 104.77, γ = 90
Cell volume	912.308 Å³, Z = 2
Axial ratios	0.5451:1:0.2920calculated from COD 9001924
Source structure	COD 9001924 (American Mineralogist, 1998) — 1 of 18 structures

Powder X-ray diffraction (calculated)

d (Å)	2.711	8.439	3.132	2.537	3.386	2.597
I/I₀	100	87.7	64.8	61.2	54.1	40.7

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9001924; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)	3.117 g/cm³calculated from COD 9001924
Streak	whitesingle sourceWikidata (CC0)

Classification

Nickel-Strunz (10th)	9.DE.10Wikidata (CC0)
Nickel-Strunz (9th)	9.DE.10Wikidata (CC0)