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Minerals - Bentorite | TerraCollect
Mineral - Bentorite
Bentorite
Ca₆Cr₂(SO₄)₃(OH)₁₂ · 26H₂O
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
Ca₆Cr₂(SO₄)₃(OH)₁₂ · 26H₂O
Unit Cell
a=22.35 c=21.41 Z=8
Physical Properties
Hardness
2
Streak
white
pink
violet
violet white
Optical Properties
Color
red
pink
violet
Birefringence
0,006
Luster
Greasy,
Earthy,
Waxy
Transparency
translucent,
transparent
Pleochroism
Farblos/Violett
Geomineralogical Properties
Crystal System
Composition
Elements
Mass
SO₃
14.99
CO₂
6.70
SiO₂
2.50
Al₂O₃
1.01
Fe₂O₃
0.10
Cr₂O₃
7.48
CaO
29.90
Karten-Ebenen
Geologische Karte
Satelliten Karte
Density
Normal (2-3,5)
Cleavage
Perfect after {100}, indistinct after {001}
Fracture
conchoidal,
uneven
Tenacity
Brittle
trigonal
Point Group
ditrigonal-pyramidal - 3m
Space Group
P31c (159)
Habit
coarse,
crusty,
massive,
prismatic
Formation
Through pyrometamorphism of calcareous sediments, triggered by natural fires involving fossil fuels (such as bitumen or gas) and associated with subsequent hydrothermal hydration
Paragenesis
Twinning
Rarity
Rare
Synonyms
Bentorite
H₂O
37.70
Israel (Gross 1980)
Groups and Members
Ettringite-Group
