Mineral - Coquimbite
Coquimbite
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
Fe²³⁺[SO₄]₃·9H₂O
Unit Cell
a=10.92 c=17.08 Z=4
Physical Properties
Hardness
2.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Imperfect after {10 1 1}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
yellowgreenvioletcolorless
Birefringence
0.009
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
trigonal
Point Group
ditrigonal-scalenohedral - 3 m
Space Group
P 3 1c (163)
Habit
crusty, massive, prismatic, tabular
Formation
Oxidation zone of sulfide deposits (e.g., pyrite), resublimation
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Coquimbite
Composition
Elements
Mass
SO₃
42.37
Fe₂O₃
28.94
H₂O
28.48
Chile (Palache et al. 1952)
Groups and Members
Coquimbite-Group