Phenacite is found in high-temperature pegmatite
veins and is associated with quartz, chrysoberyl and topaz. It has long been known from the Chrysoberyl
mine on the Takovaya stream in Russia, where large
crystals occur in mica-schist. It is also found with topaz
and amazon stone in Colorado and Maine, USA. Large
crystals of prismatic habit have been found in a Norway.
The structure consists of
a three-dimensional network of corner-linked, slightly
distorted BeO4 and fairly regular SiO4 tetrahedra. The
lattice of these materials consists of SiO4 and BeO4 tetrahedra,
which are bound to each other and form chains
oriented along the principal crystallo-graphic axis C3.
The chains form voids in the form of wide channels
～4.5? in diameter.
