Mineral - Birnessite
Birnessite
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
(Na,Ca)₀,5(Mn⁴⁺,Mn³⁺)₂O₄ · 1,5H₂O
Unit Cell
Physical Properties
Hardness
1.5
Streak
brown
Density
Normal (2-3,5)
Cleavage
Fracture
Tenacity
Brittle
Optical Properties
Color
blackgray
Birefringence
Luster
Vitreous,
Metallic
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/m (12)
Habit
coarse, spherical, massive, prismatic
Formation
Oxidation zone of manganese deposits
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Birnessite
Groups and Members
Birnessite-Group