THE MINERAL VARISCITE

Chemistry: AlPO4-2H2O, Hydrated Aluminum Phosphate
Class: Phosphates
Group: Variscite
Uses: mineral specimens and ornamental stone applications
Specimens

Variscite is a relatively rare phosphate mineral that is sometimes confused with turquoise. It is usually greener, however, than turquoise. Variscite is sometimes used as a semi-precious stone and can make distinctive color patterns that are very attractive. Occassionally it is altered into other phosphate minerals. This can occur in what were perhaps weak layers of a nodule since only portions of the variscite nodules are altered. The most common alteration mineral is crandallite, CaAl3(PO4)2(OH)5-H2O, and gives some nodules a yellow or white layer.

PHYSICAL CHARACTERISTICS:

Color is light green to emerald green, sometimes bluish-green or colorless.
Luster is vitreous or waxy.
Transparency specimens are translucent.
Crystal System is orthorhombic; 2/m2/m2/m
Crystal Habits include nodules, fine grain masses, and crusts.
Cleavage is normally not applicable, but should be good in one direction, poor in another
Fracture is conchoidal, splintery, uneven.
Hardness is variable from 3.5 - 5
Specific Gravity is approximately 2.57 (average)
Streak is white.
Associated Minerals are apatite, limonite, chalcedony, crandallite, wardite and other secondary phosphate minerals.
Other Characteristics: alteration to other phosphate minerals causes a shrinkage, yielding gaps between variscite and these other minerals.
Notable Occurances include Fairfield, Utah; Germany; Australia and Brazil.
Best Field Indicators are color, habit, associations, density and luster.

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