General Information:
Chemical Formula:
KAl3(SO4)2(OH)6
Composition:
(Molecular Weight = 414.21 gm)
Potassium 9.44 % K
Aluminum 19.54 % Al
Hydrogen 1.46 % H
Sulfur 15.48 % S
Oxygen 54.08 % O
Empirical Formula:
KAl3(SO4)2(OH)6
Environment:
Rock forming mineral where acid, often ore-bearing, solutions have altered orthoclase feldspar-rich rocks.
IMA Status:
Approved IMA 1963
Locality:
Marysvale, Utah.
Name Origin:
From the Latin alunit, meaning "alum."
Physical Properties:
Cleavage:
[0001] Good
Color:
white, gray, yellowish gray, reddish gray, or yellowish white.
Density:
2.59 - 2.9, Average = 2.74
Diaphaniety:
Transparent to translucent
Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite)., Fibrous - Cr ystals made up of fibers.
Hardness:
3.5-4 - Copper Penny-Flourite
Luminescence:
None.
Luster:
Vitreous - Pearly
Streak:
white
More details...