Mineral - Aphthitalite
Aphthitalite
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
K₃Na(SO₄)₂
Unit Cell
a=5.68 c=7.33 Z=1
Physical Properties
Hardness
3
Streak
white
Density
Normal (2-3,5)
Cleavage
Good after {100}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
whiteredyellowgreenbluecolorless
Birefringence
0.005
Luster
Vitreous,
Resinous
Transparency
translucent,
transparent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
trigonal
Point Group
ditrigonal-scalenohedral - 3 m
Space Group
P 3 m1 (164)
Habit
tabular
Formation
Through the resublimation of volcanic vapors
In evaporite deposits, through evaporation
Paragenesis
Twinning
Rotation twins after {001} or {110}
Rarity
Rarely
Synonyms
Aphthitalite
Composition
Elements
Mass
SO₃
47.46
Na₂O
10.67
K₂O
41.87
New Mexico (Palache et al. 1952)
Groups and Members
Aphthitalite-Group
Name and first discovery : Named after the Greek words "aphthitos" for "unchangeable" and "halas" for "salt", due to its stability in air.
Chemistry :
Synonyms : Aphthalite, Glaserite, Vesuvius salt
Varieties : Ammonium aphthitalite, Cuprian-manganese aphthitalite
Abbreviation : Att
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.