Emerald is one of the gem varieties of the mineral beryl and crystallises in the hexagonal system. Its intense green colour is caused by traces of chromium, or sometimes vanadium.
- Chemistry: Beryllium aluminium silicate
- Hardness: 7.5
- Refractive Index: 1.57 - 1.58
- Specific gravity: 2.69 - 2.76
- Lustre: vitreous
Emerald has been mined at Poona and west of Menzies, Western Australia . In New South Wales it has been found near Emmaville and Torrington in the New England area.
New South Wales
From 1890 to 1909, the Emerald Proprietary Company mined for emeralds north-east of Emmaville, in the New England tablelands, and produced a large quantity of pale to bright green crystals.
Emerald has also been found at Fielders Hill, near Torrington, where It occurs as strongly defined green zones in colourless beryl crystals. Cut perpendicular to the c-axis, these crystals yield a standard emerald. They can also be cut parallel to the c-axis to produce an unusual striped stone.