Description
Beryl is a mineral. It is a colorless, white, yellowish-white, yellowish-green to green, pink, bluish to greenish-blue, red, or golden-yellow aluminum-beryllium silicate. Its chemical formula is Al2Be3Si6O18. It belongs to the cyclosilicates. The mineral's hardness is 7.5 to 8 (brittle) on the Mohs scale, and its streak color is white. The mineral, which occurs in crystals, granular, compact, or radial aggregates, or pebbles, is transparent to translucent and has a vitreous, opalescent luster. The density of beryl is 2.63-2.80, and it has a hexagonal crystal structure. Pliny named beryl after the Greek word berullos (meaning "gemstone of sea-green color"). Beryl occurs in pegmatites, hydrothermal-pneumatolitic, and metamorphic rocks and is quite rare. The type locality is not further defined, but varies by variety. The mineral is found in the United States (South Dakota, Connecticut), Brazil, Germany, and Australia, among other places. The largest beryl crystal measured 18 meters in length and 3.5 meters in width. The mineral's applications include: as a raw material for beryllium, space travel, and as a (semi-)precious stone (facet stones, cabochons). In the Middle Ages, the mineral, after grinding, was said to have been used to improve visual acuity. The word "spectacles" derives from this. However, according to Pliny, Emperor Nero already saw through an emerald.
Aquamarine and the mines.
