February Stone

Across my desk….

the other day came a delicious (is the only word to describe it) amethyst, which as many of us know is the birthstone of February and the stone of the zodiac sign, Pisces.

Amethyst is probably the most interesting and well known stone of the quartz family and when you see a fine speciman you  appreciate how underrated these stones are.

The word amethyst is an ancient derivation  – Pliny said it was called this as the colour was very close but not quite to that of wine.  The word is said to be derived from the Greek word Amethustos.  Which means ‘not drunken’.  It was supposed to protect from a binge drinking session where one usually gets hammered.  Hmmmmm.

One often sees pictures of them lining the hollow cavities of geodes.  If you visit museums or minerals shops there are usually some of them on display.  Sometimes they vary in colour from deep coloured – grading into a milky quartz or a rock crystal (colourless).  Sometimes you see them with yellowy/orange zones – these are called ametrines, a variation of citrine and amethyst.  Amethyst may be heated to produce citrine.  Some of the more interesting inclusions found in amethyst are banded structures known as ‘tiger stripes or ‘zebra stripes’.

Some Gemmology:  Amethyst is silicon dioxide SiO2.  Crystal System: Trigonal, Uniaxial positive, RI 1.53to 1.56 DR 0.009, SG 2.6 to 2.65.

Amethyst is a lovely stone but not very hard at MOH 7 (same as a hard steel file) – this can abrade fairly easily over time and wear.  Should not be worn as an everyday ring.  Avoid leaving amethyst in strong light as the colour may fade.

Note:  the stone pictured is not the one that passed my desk.  This is one taken from a google search to represent a typical colour of a nice amethyst.

~ by Jill Towers on February 19, 2012.

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