Mineral - Olmiite
Olmiite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
CaMn²⁺[SiO₃(OH)](OH)
Unit Cell
a=9.25 b=9.08 c=10.34 Z=8
Physical Properties
Hardness
5 - 5.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
redpink
Birefringence
0.031
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pbca (61)
Habit
blocky, dipyramidal, sheaf-shaped, spherical, prismatic, tabular
Formation
Hydrothermal, as a late-stage process in manganese deposits resulting from the interaction of hot, siliceous fluids with pre-existing ores (particularly hausmannite) under low-grade metamorphic conditions
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Olmiite
Composition
Elements
Mass
SiO₂
29.47
FeO
0.18
MnO
29.28
CaO
31.33
H₂O
8.89
South Africa (Bonazzi et al. 2007)