Silicates: Beryl

Composition: Be₃Al₂Si₆O₁₈; sodium, potassium and other alkalis may substitute for aluminium or occupy vacant sites in the structure

Crystal system: Hexagonal; crystals commonly prismatic, also massive

5.5.1
beryl crystal in quartz
ME USA

Properties:

• Vitreous lustre
• Variable color; white, pale green or blue, dark green, yellow or pink
• White streak
• Knife does not scratch (Mohs Hardness 8)
• Average density
• Cleavage rarely apparent
• Smooth fracture
• Not ferromagnetic
• Does not react with hydrochloric acid (HCl)

Occurrence:

Beryl is the most common beryllium mineral. It occurs in pegmatite dykes and hydrothermal vein and replacement deposits, particularly where these intrusions and veins cut ultramafic rocks .

5.5.2
beryl crystal in quartz
 ME USA

Beryl is the most important source of beryllium metal that is used in light weight alloys. Gem quality beryl occurs in a variety of colors including pale green and blue (aquamarine), dark green (emerald), yellow (helidor) and pink (morganite) as a result of differing contents of trace elements, especially iron, titanium, chromium and vanadium.