Mineral - Franckeite
Franckeite
Chemical Properties
Mineral Class
Sulfides and sulfosalts
Toxicity
low
Formula
Fe²⁺(Pb,Sn²⁺)₆Sn⁴⁺₂Sb₂S₁₄
Unit Cell
a=3.67 b=6.26 c=17.42 α=95° β=96° γ=90° Z=2
Physical Properties
Hardness
2.5 - 3
Streak
blackgraygray black
Density
Heavy (3,5-6)
Cleavage
Perfect after {010}
Fracture
Tenacity
Inelastic-flexible
Optical Properties
Color
blackgray
Birefringence
Luster
Metallic
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
triclinic
Point Group
triclinic-pinacoidal - 1
Space Group
P 1 (2)
Habit
spherical, rosette, tabular
Formation
hydrothermal
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Franckeite
Composition
Elements
Mass
Pb
50.57
Fe
2.48
Zn
1.22
Sn
12.34
Sb
10.51
S
21.04
Bolivia (Palache et al. 1952)
Groups and Members
Franckeite-Group