Mineral - Bannisterite
Bannisterite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
(Ca,K,Na)(Mn²⁺,Fe²⁺)₁₀(Si,Al)₁₆O₃₈(OH)₈ · nH₂O
Unit Cell
a=22.30 b=16.40 c=24.70 β=94° Z=4
Physical Properties
Hardness
4
Streak
brown
Density
Normal (2-3,5)
Cleavage
Perfect after {001}
Fracture
smooth
Tenacity
Optical Properties
Color
blackbrown
Birefringence
0.045
Luster
Resinous
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/c (15)
Habit
leafy, blocky, massive, prismatic, tabular
Formation
Through metamorphism of Mn-Zn ore deposits
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Bannisterite
Composition
Elements
Mass
SiO₂
45.40
Al₂O₃
3.84
Fe₂O₃
2.10
FeO
16.50
MnO
19.90
MgO
0.47
CaO
1.55
Na₂O
0.51
K₂O
0.92
H₂O
7.82
Australia (Smith & Frondel 1968)
Name and first discovery: Named after the British mineralogist Dr Frederick Allan Bannister (1901 - 1971). First described in 1967.
Chemism:
Synonyms:
Varieties:
Abbreviation: Ban
Literature
Smith, M. L., & Frondel, C. (1968). The related layered minerals ganophyllite, bannisterite, and stilpnomelane1. Mineralogicalmagazine and journal of the Mineralogical Society, 36(283), 893-913.