Mineral - Cronstedtite
Cronstedtite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Fe²⁺₂Fe³⁺((Si,Fe³⁺)₂O₅)(OH)₄
Unit Cell
a=5,51 c=7,11 Z=
Physical Properties
Hardness
3.5
Streak
green black
Density
Normal (2-3,5)
Cleavage
j
Fracture
smooth
Tenacity
Elastic-flexible
Optical Properties
Color
blackbrowngraybrown black
Birefringence
Luster
Metallic,
Waxy
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
trigonal
Point Group
Space Group
Habit
coarse, wedge-shaped, spherical, massive, pyramidal, rosette, Tetrahedron
Formation
Sekundär, hydrothermal in Eisen-Lagerstätten
Paragenesis
Twinning
Durchdringungszwillinge erzeugen pseudohexagonale Kristalle
Rarity
Rarely
Synonyms
Cronstedtite
Composition
Elements
Mass
SiO₂
16,40
Al₂O₃
0,91
Fe₂O₃
29,70
FeO
41,84
CaO
1,30
H₂O
10,15
Rumänien
Groups and Members
Kaolinit-Serpentin-Gruppe
Serpentin-Subgruppe