General Information:
Chemical Formula:KAl3(SO4)2(OH)6
Composition:(Molecular Weight = 414.21 gm)Potassium 9.44 %
K Aluminum 19.54 %
AlHydrogen 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
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