• 
• 
• 
• 

Amethyst

Crystalline quartz in shades of purple, lilac, or mauve is called amethyst, a stone traditionally worn to guard against drunkenness, and to instil a sober and serious mind. Amethyst is dichroic, showing a bluish or reddish purple tinge when viewed from different angles. Usually faceted as a mixed-or step cut, amethyst has distinctive inclusions which look like tiger stripes, thumb-prints, or feathers. Some amethyst is heat treated to change the colour to yellow, producing citrine. Crystals which are part amethyst and part citrine are called ametrine.

Occurrence

Amethyst is found in alluvial deposits or in geodes. Some of the largest geodes containing amethyst are in Brazil. Amethyst from the Urals (Russia) has a reddish tinge; Canadian amethyst is violet. Other localities include Sri Lanka, India, Uruguay, Madagascar, the USA, Germany, Australia, Namibia, and Zambia.

Remark

Poor-quality material is often tumbled to make beads. If a stone is pale it may be set in a closed setting or have foil placed behind it to enhance the colour. Amethyst has been imitated by glass and synthetic corundum.

Crystal structure	Trigonal
Composition	Silicon dioxide
Hardness	7
SG	2.65
Rl	1.54-1.55
DR	0.009
Lustre	Vitreous