Mineral - Cryptomelane
Cryptomelane
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
K(Mn⁴⁺₇Mn³⁺)O₁₆
Unit Cell
a=9,96 b=2,87 c=9,71 β=91° Z=1
Physical Properties
Hardness
5 - 6.5
Streak
blackbrownbrown black
Density
Cleavage
nd
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blackbrowngray
Birefringence
Luster
Pitchy,
Resinous,
Earthy
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
Space Group
Habit
dendritic, coarse, spherical, massive, kidney-shaped, stalactitic, grape-shaped
Formation
Sekundär, in der Oxidationszone von Mangan-Lagerstätten
Paragenesis
Twinning
Nach (010) und (00 1 )
Rarity
Common
Synonyms
Cryptomelane
Composition
Elements
Mass
SiO₂
0,58
TiO₂
0,01
MnO₂
83,13
Al₂O₃
0,37
Fe₂O₃
0,46
MnO
2,08
CuO
0,12
ZnO
5,23
MgO
0,05
CaO
0,27
BaO
0,13
Na₂O
0,44
K₂O
3,51
H₂O
2,57
P₂O₅
0,06
Arizona
Groups and Members
Hollandit-Supergruppe
Coronadit-Gruppe