Mineral Factbook

Pargasite

NaCa2(Mg4Al)(Si6Al2)O22(OH)2IMA symbol: Prgredefined

Pargasite is a silicate mineral with the formula NaCa2(Mg4Al)(Si6Al2)O22(OH)2, crystallizing in the monoclinic system. It has a Mohs hardness of 5.5, a calculated density of 3.284 g/cm3.

Photos

Pargasite specimen photo
Parent Géry · CC BY-SA 3.0 · Commons
Pargasite specimen photo
Parent Géry · CC BY-SA 3.0 · Commons
Pargasite specimen photo
Parent Géry · CC BY-SA 3.0 · Commons
Pargasite specimen photo
Géry PARENT · Public domain · Commons

Crystallography

Crystal systemmonoclinic crystal systemWikidata (CC0)
Space groupC 1 2/m 1
Cell (Å, °)a = 9.9448, b = 18.0171, c = 5.2829; α = 90, β = 105.445, γ = 90
Cell volume912.387 ų, Z = 2
Axial ratios0.5520:1:0.2932calculated from COD 9015859
Source structureCOD 9015859 (American Mineralogist, 2012) — 1 of 62 structures

Powder X-ray diffraction (calculated)

2θ (degrees, Cu Kα1)I/I₀ (max 100)
d (Å)3.3692.5472.6982.9332.5873.282
I/I₀10085.876.476.168.367.4

xrd-v1: CuKa1 1.5406A, 2theta 5-90, top10, Imax=100, no DW/PO. Computed from COD 9015859; idealized occupancies, no preferred orientation.

Physical properties

Density (calculated)3.284 g/cm³calculated from COD 9015859
Hardness (Mohs)
5.5single sourceWikidata (CC0)

Chemistry (calculated)

Molecular weight835.82 g/molcalculated from the IMA formula
Composition (wt%)Na 2.75%, Ca 9.59%, Mg 11.63%, Al 9.68%, Si 20.16%, O 45.94%, H 0.24%

Classification

Nickel-Strunz (10th)9.DE.15Wikidata (CC0)
Nickel-Strunz (9th)9.DE.10Wikidata (CC0)
Dana (8th)66.1.3a.12Wikidata (CC0)