Beryl is an important source of beryllium. The mineral has several gem varieties, the most valuable of which is emerald. Most beryl is found in pegmatite dykes, where large crystals are intergrown with quartz and feldspar. However, the emerald variety also occurs in altered limestone and in various metamorphic rocks.
With bertrandite (beryllium aluminum silicate), beryl is the main commercial ore for beryllium, a metal that does not occur in free state. Beryllium has several properties that make it of great use in industry. This metal is lighter and stronger than aluminum, is resistant to corrosion, and has a high melting point of 2,392 degrees F. (1,278 degrees C.). Unfortunately, it is so rare and expensive to extract and purify that it costs about twice that of aluminum.
The color of beryl can vary enormously and several of the precious and semiprecious forms of the mineral have been given their own names. For example, it may be colorless, blue (aquamarine), golden (heliodor), green (emerald), pink (morganite), red, or white.
Beryl forms in prismatic crystals that sometimes terminate in small pyramids. It crystals can vary in size to a large extent. One weighing 200 tons was mined in Minas Gerais, Brazil, and crystals about 20 feet long and 7 feet across have been found in Albany, Maine, and in the Black Hills of South Dakota. Sometimes beryl forms in massive habits that can be mistaken for quartz.
Most beryls found in BC are found in pegmatites. Berysl found at Logjam Creek, Horseranch Range, and Dortatelle Creek in the Cassiar area are small, opaque, poorly formed crystals of bluish green color. A few well-developed pale bluish green beryls have been found at Fort Graham in the Butte Range. Beryls have been identified at the Bonanza mica mine near Tete Jaune Cache, and pegmatite dykes on Mount Begbie also contain beryls.
Pegmatite dykes and loose blocks are prevalent in the Kootenays. Most beryls in this area are very pale, with the occasional blue-green crystals occurring around Angus, Porcupine, White, Skookumchuk and Hellroaring creeks. Pockets of pegmatite containing yellow to yellow-green to aqua beryls have been found in the Slocan valley.