Beryl (Aquamarine) 

(Silicate-Ring)

Be₃Al₂Si₆O₁₈

Hardness: 7.5 - 8.0

Specific Gravity: 2.7 - 2.9

Characteristics: Green (emeralds), greenish-blue (as shown), yellow, white, pink, or colorless; transparent to translucent; vitreous luster; hexagonal crystals; poor cleavage and chonchoidal fracture; insoluble in most acids.

Found in granitic intrusives, pegmatites, and biotite schists.

Fine beryl crystals are used as gemstones; Primary source of beryllium which is used in such things as fluorescent lamps, x-ray tubes and some alloys used in aircraft.

(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)