Phenakite

The type locality of Phenakite, where this mineral was first described, is Malyshevo, near Yekaterinburg, Sverdlovskaya Oblast, in the Ural Mountains of Russia. Lustrous, gemmy, prismatic crystals that are twinned are mined in Mogok and Mongmit, Burma (Myanmar). The largest crystals of Phenakite to date have come from the Tangen Feldspar Mine, Kragerø, Telemark, Norway, as gray and white crystals, often still in matrix and somewhat opaque. 

Highly lustrous Phenakite crystals with multiple complex faces have been found in the Salistone Mine, Jos Plateau, Nigeria; and colorless crystals and clusters from the Stiepelmann Mine, near Klein Spitzkopje, Erongo Region, Namibia. Prismatic colorless Phenakite crystals have recently been coming from the Anjanabonoina pegmatite, Betafo District, Antananarivo Province, Madagascar.

Complex, colorless floater crystals of Phenakite are classics from Rio Piracicaba, Minas Gerais, Brazil. In the U.S., stubby, usually cloudy crystals are well known at Mt. Antero, Chaffee Co., Colorado. Small white crystal clusters come from the Mount Wheeler Mine, near Mount Washington, White Pine Co., Nevada. Small Phenakite microcrystals have come from the Morefield Mine, Winterham, Amelia Co., Virginia; and the Lord Hill Quarry, Stoneham, Oxford Co., Maine.

Quartz - Lower hardness and crystals striations are horizontal.
Topaz - Different crystal shape, and has perfect cleavage.
Danburite - Different crystal shape and distinct termination.