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Friday, October 10, 2014
Tourmaline - October Birthstone
Tourmaline is both the modern alternative birthstone for October and the stone of the 8th wedding anniversary. It was only recognised by scientists in the 1800’s, after being confused for other gemstones for centuries. This is because Tourmaline has one of the widest colour ranges of any gemstone; from delicate pinks, through rich greens to deep blues. In fact, the name tourmaline comes from the word ‘toramalli’, which means ‘mixed gems’ in the Sri-Lankan language Sinhalese.
Different colours of tourmaline are known by different names. Red/dark pink tourmaline is known as rubelite, greenish blue as indicolite, black tourmaline as schorl, brown tourmaline as dravite and the bi-coloured tourmaline with pink in the centre and green outer as watermelon. The rarest colour to find is pink tourmaline.
As tourmaline was discovered fairly recently (in geology terms anyway) it doesn't have the rich ancient history of other birthstones. The Russian Romanov royal dynasty was particularly fond of tourmaline. Catherine the Great owned several, including this fruity brooch known as ‘Caesars Ruby’.
Tourmaline has a rather strange property; it can produce an electric charge! When heated it produces a pyroelectric charge and when pressure is applied it produces piezoelectricity. Because of this, tourmaline was used as an electrical component in sonar, especially during WW2, when demand for the mineral increased. Benjamin Franklin is also believed to have used tourmaline in his studies of electricity.
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