General Information:
Chemical Formula:
Al(OH)3
Composition:
(Molecular Weight = 78.00 gm)
Aluminum 34.59 % Al
Hydrogen 3.88 % H
Oxygen 61.53 % O
Empirical Formula:
Al(OH)3
Environment:
Lateritic soils developed on alunimous rocks in areas of high rainfall.
IMA Status:
Approved IMA 1960
Locality:
Bauxite deposits of Arkansas, USA.
Name Origin:
Named after the American collector, G. Gibbs (1776-1833).
Physical Properties:
Cleavage:
[001] Perfect
Color:
bluish, green, green white, gray, or gray white.
Density:
2.3 - 2.4, Average = 2.34
Diaphaniety:
Translucent to transparent
Habits:
Spherical - Spherical, rounded aggregates., Stalactitic - Shaped like pendant columns as stalactites or stalagmites (e.g. calcite)., Earthy - Dull, clay-like texture with no visible c rystalline affinities, (e.g. howlite).
Hardness:
2.5-3 - Finger Nail-Calcite
Luminescence:
None.
Luster:
Vitreous - Pearly
Streak:
white
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