Phenakite

Formula: Be2SiO4Mohs scale hardness: 7,5–8Specific gravity: 2.93–3Phenakite or phenacite is a fairly rare nesosilicate mineral consisting of beryllium orthosilicate, Be2SiO4.Phenakite crystal from Mount Ikaka, Madagascar Phenakite is found in high-temperature pegmatite veins and in mica-schists associated with quartz, chrysoberyl, apatite and topaz. It has long been known from the emerald and chrysoberyl mine on the Takovaya stream, near Yekaterinburg in the Urals of Russia, where large crystals occur in mica-schist. It is also found with topaz and amazon-stone in the granite of the Ilmen Mountains in the southern Urals and of the Pikes Peak region in Colorado (USA). Large crystals of prismatic habit have been found in a feldspar quarry at Kragero in Norway. Framont near Schirmeck in Alsace is another well-known locality. Still larger crystals, measuring 1 to 2 in. in diameter and weighing 28 lb (13 kg). have been found at Greenwood in Maine, but these are pseudomorphs of quartz after phenakite.The indices of refraction are higher than those of quartz, beryl or topaz; a faceted phenakite is consequently rather brilliant and may sometimes be mistaken for diamond.References

  1. https://en.wikipedia.org

  2. https://en.wikipedia.org/wiki/Phenakite

  3. https://commons.wikimedia.org/wiki/File:Phenakite-tmu02d.jpg