Mineral - Manganite
Manganite
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
Mn³⁺O(OH)
Unit Cell
a=8.94 b=5.28 c=5.74 β=90° Z=8
Physical Properties
Hardness
4
Streak
brown
Density
Heavy (3,5-6)
Cleavage
Perfect after {010}, distinct after {110} and {001}
Fracture
splintery
Tenacity
Brittle
Optical Properties
Color
black
Birefringence
0.280
Luster
Metallic
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
blocky, acicular, prismatic
Formation
(1) Primarily through hydrothermal precipitation in low-temperature veins or fissures.
(2) Secondarily as a typical alteration product of manganese-bearing rocks/minerals under oxidizing conditions in the oxidation zone or contact metamorphic zone of sedimentary deposits.
Paragenesis
Twinning
Contact twins after {012}
Rarity
Rather rare
Synonyms
Manganite
Composition
Elements
Mass
Al₂O₃
0.30
MnO
79.55
(Cu,Pb)O
0.10
CaO
0.10
BaO
0.15
(Na,K)₂O
0.22
OH
19.59
Germany (Palache et al. 1952)