Mineral Factbook

Zoisite

Ca2Al3[Si2O7][SiO4]O(OH)IMA symbol: Zograndfathered

Zoisite is a silicate mineral with the formula Ca2Al3[Si2O7][SiO4]O(OH), crystallizing in the orthorhombic system. It has a Mohs hardness of 6-6.5, typically white, brown, gray or green in color, with a pearly or vitreous luster, a specific gravity of 3.25-3.37. Its streak is red.

Photos

Zoisite specimen photo
Photograph by Mike Peel (www.mikepeel.net). · CC BY-SA 4.0 · Commons
Zoisite specimen photo
Photograph by Mike Peel (www.mikepeel.net). · CC BY-SA 4.0 · Commons
Zoisite specimen photo
Parent Géry · CC BY-SA 3.0 · Commons
Zoisite specimen photo
Stefan Kühn · CC BY-SA 3.0 · Commons

Crystallography

Crystal systemorthorhombic crystal systemWikidata (CC0)
Space groupP n m a
Cell (Å, °)a = 16.2004, b = 5.5529, c = 10.0423; α = 90, β = 90, γ = 90
Cell volume903.397 ų, Z = 4
Axial ratios2.9175:1:1.8085calculated from COD 9016180
Source structureCOD 9016180 (American Mineralogist, 2012) — 1 of 31 structures

Physical properties

Density (calculated)3.333 g/cm³calculated from COD 9016180
Hardness (Mohs)
6.5single sourceWikidata (CC0)
6-6.5single sourceDana, System of Mineralogy, 6th ed. (1892)
Specific gravity
3.25-3.37 g/cm3corroboratedDana, System of Mineralogy, 6th ed. (1892)
Color
brown, gray, green, red, white, yellowsingle sourceDana, System of Mineralogy, 6th ed. (1892)
Streak
redsingle sourceDana, System of Mineralogy, 6th ed. (1892)
Luster
pearly, vitreoussingle sourceDana, System of Mineralogy, 6th ed. (1892)

Chemistry (calculated)

Molecular weight454.36 g/molcalculated from the IMA formula
Composition (wt%)Ca 17.64%, Al 17.82%, Si 18.54%, O 45.78%, H 0.22%

Classification

Nickel-Strunz (10th)9.BG.10Wikidata (CC0)
Nickel-Strunz (9th)9.BG.10Wikidata (CC0)
Dana (8th)58.2.1b.1Wikidata (CC0)