The beryl group of minerals and gemstones

Minerals in the beryl group are silicates of beryllium and aluminium, having the chemical formula Be3Al2(SiO3)6. Beryl is found as barrel-formed crystals. The hardness of the crystals are of the grade 7.5 - 8.0. on Mohs scale. Beryl is usually found in granitic pegamitic rocks. The crystals of beryl are six-sided (hexagonal) columns.

Beryl often contains dissolved elements giving colour to the crystal. Beryl without distinct inclusions and without uneven colour are used as gemstones. Beryl not of gemstone quality is most often called only beryl. There are the following types of beryl gemstones differing in their colour:

Emerald: This is deep green beryl. Larger specimens without easily visible inclutions of foreign materials are rare and expensive. The colour is produced by cromic oxide dissolved in the crystal substance. Vanadium and iron may also effect the colouring shade.

Aquamarine: Aquamarine means sea water. The colour is skyblue, sea blue or greenish blue. The colour is due to traces of iron in the crystal framework.

Morganite: This variant has a pink color. It is an extreemely rare and expensive stone.

Bixbite: This is red beryl. Like morganites, specimens are rare and expensive.

Golden beryl: This variant is golden yellow.

Goshenite: This is coluorless beryl. It is found at the place Goshen in massechusets. Even though the variant is rare, the value is moderate due to lack of optical refractive brilliance.