Mineral - Zoisite
Zoisite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
(CaCa)(AlAlAl)O[Si₂O₇][SiO₄](OH)
Unit Cell
a=16.19 b=5.55 c=10.03 Z=4
Physical Properties
Hardness
6 - 7
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {010}, Imperfect after {100}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
grayredyellowgreenbluepinkcolorless
Birefringence
0..018
Luster
Vitreous,
Pearly
Transparency
translucent,
transparent
Pleochroism
Grün-Gelb-Blau-Violett-Rot
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pnma (62)
Habit
blocky, wedge-shaped, massive, prismatic, radial
Formation
(1) Metamorphic, formed by the transformation of calcium-rich rocks under medium- to high-grade pressure-temperature conditions characteristic of the blue schist or eclogite facies.
(2) Hydrothermal, formed as a product of the decomposition of plagioclases in igneous rocks or within alpine fractures.
Paragenesis
Twinning
Rarity
Common
Synonyms
Zoisite
Composition
Elements
Mass
SiO₂
39.55
Al₂O₃
33.39
Fe₂O₃
0.04
V₂O₃
0.20
MgO
0.07
CaO
24.44
SrO
0.05
H₂O
2.00
Tanzania (Dana 1895)