Taranakite

K₃Al₅(PO₃OH)₆(PO₄)₂·₁₈H₂OIMA symbol: Targrandfathered

Taranakite is a phosphate, arsenate, or vanadate mineral with the formula K3Al5(PO3OH)6(PO4)2·18H2O, crystallizing in the trigonal system. It has a calculated density of 2.145 g/cm3. Its streak is white.

Photos

Crystallography

Crystal system	trigonal crystal systemWikidata (CC0)
Space group	R -3 c :H
Cell (Å, °)	a = 8.7025, b = 8.7025, c = 95.05; α = 90, β = 90, γ = 120
Cell volume	6234.06 Å³, Z = 6
Axial ratios	1.0000:1:10.9221calculated from COD 9013146
Source structure	COD 9013146 (Inorganica Chimica Acta, 1998)

Powder X-ray diffraction (calculated)

d (Å)	15.842	3.814	3.137	7.444	3.587	2.817
I/I₀	100	26.2	20.9	16.7	13.3	12.9

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9013146; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)	2.145 g/cm³calculated from COD 9013146
Streak	whitesingle sourceWikidata (CC0)

Chemistry (calculated)

Molecular weight	1342.3 g/molcalculated from the IMA formula
Composition (wt%)	K 8.74%, Al 10.05%, P 18.46%, O 59.6%, H 3.15%

Classification

Nickel-Strunz (10th)	8.CH.25Wikidata (CC0)
Nickel-Strunz (9th)	8.CH.25Wikidata (CC0)