Mineral - Alstonite
Alstonite
Chemical Properties
Mineral Class
Carbonates
Toxicity
none
Formula
BaCa(CO₃)₂
Unit Cell
a=30.14 b=17.40 c=6.12 α=90° β=90° γ=90° Z=24
Physical Properties
Hardness
4 - 4.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Imperfect after {110}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
whitegrayyellowpinkcolorless
Birefringence
0.146
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
triclinic
Point Group
triclinic-pinacoidal - 1
Space Group
P 1 (2)
Habit
coarse, dipyramidal, massive, Scalenohedron
Formation
In low-temperature hydrothermal Pb-Zn deposits, in carbonatites
Paragenesis
Twinning
Pseudohexagonal twins
Rarity
Rather rare
Synonyms
Alstonite
Composition
Elements
Mass
CO₂
29.41
CaO
17.60
SrO
4.25
BaO
48.54
England (Palache et al. 1952)
Name and first discovery : Named after the type locality in the Alston Moor district of Cumbria, England, UK. The mineral was first described in 1841 by August Breithaupt.
Chemistry : Polymorph to monoclinic barytocalcite and trigonal paralstonite
Synonyms : Bromlite
Varieties :
Abbreviation : Asn
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.