Afghanite

(Na,K)₂₂Ca₁₀(Si₂₄Al₂₄)O₉₆(SO₄)₆Cl₆IMA symbol: Afgapproved

Afghanite is a silicate mineral with the formula (Na,K)22Ca10(Si24Al24)O96(SO4)6Cl6, crystallizing in the trigonal system. It has a calculated density of 2.532 g/cm3. Its streak is white.

Photos

Crystallography

Crystal system	trigonal crystal systemWikidata (CC0)
Space group	P 3 1 c
Cell (Å, °)	a = 12.7961, b = 12.7961, c = 21.4094; α = 90, β = 90, γ = 120
Cell volume	3035.92 Å³, Z = 2
Axial ratios	1.0000:1:1.6731calculated from COD 9016533
Source structure	COD 9016533 (American Mineralogist, 2012) — 1 of 2 structures

Powder X-ray diffraction (calculated)

d (Å)	3.299	3.694	4.82	2.133	2.676	1.794
I/I₀	100	96.1	40.9	34.7	34	26.4

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9016533; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)	2.532 g/cm³calculated from COD 9016533
Streak	whitesingle sourceWikidata (CC0)

Classification

Nickel-Strunz (10th)	9.FB.05Wikidata (CC0)
Nickel-Strunz (9th)	9.FB.05Wikidata (CC0)
Dana (8th)	76.2.5.1Wikidata (CC0)