Mineral - Franklinite
Franklinite
Chemical Properties
Mineral Class
Oxides and Hydrxides
Toxicity
none
Formula
(Zn,Mn²⁺,Fe²⁺)(Fe³⁺,Mn³⁺)₂O₄
Unit Cell
a=8.47 Z=8
Physical Properties
Hardness
6 - 6.5
Streak
brownredred brown
Density
Heavy (3,5-6)
Cleavage
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
blackbrownred
Birefringence
Luster
Metallic
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
isometric
Point Group
hexoctahedral - 4/m 3 2/m
Space Group
Fd 3 m (227)
Habit
massive, Octahedron
Formation
Under high-grade metamorphic conditions (granulite facies) through the recrystallization of zinc-, manganese-, and iron-rich carbonate precursor sediments within a stratiform, hydrothermally influenced deposit
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Franklinite
Composition
Elements
Mass
SiO₂
0.72
Fe₂O₃
66.58
MnO
9.96
ZnO
20.77
MgO
0.34
CaO
0.43
H₂O
0.71
New Jersey (Palache et al. 1952)
Groups and Members
Spinel-Supergroup
Oxyspinel-Group
Spinel-Subgroup