Mineral - Alumohydrocalcite
Alumohydrocalcite
Chemical Properties
Mineral Class
Carbonates
Toxicity
none
Formula
CaAl₂(CO₃)₂(OH)₄ · 4H₂O
Unit Cell
a=6.50 b=14.46 c=5.68 α=96° β=93° γ=82° Z=2
Physical Properties
Hardness
2.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {100}, imperfect after {010}
Fracture
Tenacity
Brittle
Optical Properties
Color
whitepink
Birefringence
Luster
Vitreous,
Pearly
Transparency
translucent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
triclinic
Point Group
Space Group
Habit
spherical, acicular, radial
Formation
Secondary, hydrothermal, through the reaction of carbonate solutions with primary minerals
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Alumohydrocalcite
Composition
Elements
Mass
CO₂
26.40
Al₂O₃
22.00
Cr₂O₃
8.30
CaO
16.50
H₂O
26.60
California (Palache et al. 1952)
Groups and Members
Dresserite-Group
Name and first discovery : Named for its chemical composition of aluminum, water, and calcium. Discovered in Russia in 1926.
Chemistry :
Synonyms : Aluminohydrocalcite, Khakassite
Varieties : Chromium alumohydrocalcite, knipovichite
Abbreviation : Ahcal
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.