Photo of Phenakite in Processed & Rough Form
Phenakite is a mineral with a hardness of 8 out of 10 on the Mohs scale of mineral hardness [?]. These Trigonally structured gems are made of beryllium silicate, their full chemical compound being Be2SiO4.
Phenakite is a rare beryllium silicate with a hexagonal crystal system. It an attractive hard mineral that resembles quartz.
It appears as white or colorless rhombohedral crystals or stubby prisms terminated by multiple rhombohedral faces. Twinned crystals are also common. It may be colorless, yellow, pink, or brown. There are occasional chatoyant specimens, and four-rayed star stones with a brownish tint have been reported from Sri Lanka.
It is very hard, fairly light, with imperfect cleavage. It is transparent with very bright vitreous luster, and looks very much like quartz, but is much harder and has different twinned forms. It is infusible and insoluble in acids.
Phenakite is found in high-temperature pegmatite veins and in mica schists associated with quartz, chrysoberyl, beryl, apatite, and topaz.
The best crystals are found in emerald-bearing mica schists in the Urals (Russia), in the pegmatites of Minas Gerais (Brazil) in at Pike's Peak region, Topaz Butte, in Colorado (USA), in Kragero (Norway). It is also found in Val Vigezzo (Domodossola, Italy).
Phenakite is also spelled as "phenacite."
It is often confused with rock crystal (quartz) and topaz.
The specific gravity [?] for Phenakite is 2.96, its refractive index [?] is 1.65-1.67, and its double refraction [?] is 0.015.
History
Phenakite derives its name from the Greek word for "deceiver", because it looks very much like quartz in its colorless form.
Industrial Usages
Phenakite is suitable as gemstone but has almost little fire, though some really brilliant specimens have been mistaken for diamond. It is usually cut as faceted stones of moderate brilliance and prized by collectors.
The use of phenakite in jewelry is an example of how a natural gemstone is often used to imitate another natural gemstone, due to its near resemblance.
Phenakite crystals occurring as inclusions in emerald usually indicate man-made origin. It has been produced synthetically.
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