Mineral - Scolecite
Scolecite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
CaAl₂Si₃O₁₀ · 3H₂O
Unit Cell
a=18.51 b=18.98 c=6.53 β=91° Z=8
Physical Properties
Hardness
5 - 5.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {110} and {1 1 0}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
whitecolorless
Birefringence
0.010
Luster
Vitreous,
Silky
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-domatic - m
Space Group
Cc (9)
Habit
fibrous, massive, acicular, prismatic
Formation
(1) Hydrothermal, formed by precipitation from low-temperature aqueous solutions in cavities within igneous rocks, primarily as a late-stage crystallization product in basaltic lava.
(2) Metamorphic, formed during low-grade regional metamorphism in the zeolite facies at temperatures below 250 °C.
(3) As a result of alpine fracturing (secondary) due to hydrothermal mobilization in metamorphic rocks such as gneisses or amphibolites
Paragenesis
Twinning
Rarity
Common
Synonyms
Scolecite
Composition
Elements
Mass
SiO₂
45.16
Al₂O₃
25.90
CaO
14.86
Na₂O
0.16
K₂O
0.06
H₂O
13.66
India (Dana 1895)
Groups and Members
Zeolite-Group
Natrolite-Subgroup