Variscite (#87)

A polished slice showing light to dark green 'pebbles' of variscite in an aggregate.
North America Lucin, Pilot Range, Box Elder County, Utah 3 ¾" x 2 ½" x ¼"


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Variscite is a phosphate mineral, AIPO · 2H2O. Al is the chemical symbol for aluminum, P is phosphorus, O is oxygen, and of course, H2O is the water molecule. The presence of H2O at the end of any mineral formula indicates that water molecules constitute a necessary part of the chemistry and have a distinct role in the crystal structure (meaning, the arrangement of the atoms). But it isn't liquid water, just individual water molecules chemically bonded in the crystal structure.

Variscite is an uncommon mineral, but it is found in several localities around the world. This locality (Lucin, Utah) is well-known for producing beautiful material for making polished slabs. Although the hardness of variscite is only 3.54.5, it is sometimes used in jewelry as polished stones. The color range seen in this specimen is only part of the known range. In specimens containing appreciable iron, it occurs as brilliant clusters of red micro-crystals, and in the blue-green varieties it is sometimes confused with turquoise. There is evidence that, at least in variscite from some localities, the green color is caused by the substitution of minor chromium (Cr) for some aluminum.