Mineral - Ilvaite
Ilvaite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca(Fe²⁺)₂Fe³⁺[O|OH|Si₂O₇]
Unit Cell
a=8.80 b=13.02 c=5.85 Z=4
Physical Properties
Hardness
5.5 - 6
Streak
blackbrownbrown black
Density
Heavy (3,5-6)
Cleavage
Distinct after {001} and {010}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
black
Birefringence
0.156
Luster
Metallic
Transparency
opaque
Pleochroism
Schwarz/Grün/Braun
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
blocky, massive, prismatic, radial
Formation
Contact metasomatic (skarn) through the supply of iron-rich hydrothermal fluids into carbonate rocks
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Ilvaite
Composition
Elements
Mass
SiO₂
29.30
Fe₂O₃
20.30
FeO
33.50
MnO
1.97
CaO
13.71
H₂O
1.90
Greenland (Dana 1895)
Groups and Members
Lawsonite-Group