Mineral - Witherite
Witherite
Chemical Properties
Mineral Class
Carbonates
Toxicity
high
Formula
BaCO₃
Unit Cell
a=5.31 b=8.90 c=6.43 Z=4
Physical Properties
Hardness
3 - 3.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Imperfect after {110}, indistinct after {010}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
whitegrayorangecolorless
Birefringence
0.148
Luster
Vitreous,
Greasy
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pnma (62)
Habit
blocky, dipyramidal, spherical, prismatic, tabular, grape-shaped
Formation
Hydrothermal as a vein mineral in medium- to low-temperature lead-zinc ore deposits, formed by precipitation from barium-bearing solutions in the presence of carbonates.
Paragenesis
Twinning
Mimetic contact twins after {110}
Rarity
Rather rare
Synonyms
Witherite
Composition
Elements
Mass
CO₂
22.50
CaO
0.08
SrO
0.68
BaO
77.15
England (Palache et al. 1952)
Groups and Members
Aragonite-Group