Home ยป Quartz

Amethyst


Properties
Chemical Composition: 
Silica (Silicon Dioxide) SiO2
Classification / Type: 
-
Colors / Varieties: 
Violet
Crystal System / Forms: 
Trigonal System
Hardness: 
7
Specific Gravity: 
2.63 - 2.68
Cleavage / Fracture: 
No distinct cleavage / conchoidal to uneven fracture
Optic Character: 
Anisotropic, D.R.; Uniaxial positive. May exhibit a bull's eye optic figure (quartz rotates the plane of polarisation parallel to the c-axis).
Lustre: 
Vitreous.
Refractive Index / Birefringence: 
1.544 - 1.553 / 0.009. Range: 1.535 - 1.560
Pleochroism: 
Purple / Pinkish Purple
Dispersion: 
0.013
Magnification: 
Liquid and two phase, color zoning, negative crystals, zebra-stripe finger prints (structural), crystal inclusions, green fuchsite mica flakes / platelets in aventurine quartz, rutile / tourmaline needles in sagenitic quartz. Brazil law twinning is seen in natural quartz.
U.V. Fluorescence: 
Variable.
Spectrum: 
Not characteristic
Cause of Color: 
Color center caused by natural or artificial irradiation of Iron (Fe2+ / Fe3+) bearing quartz.
Treatment (Enhancement): 
Specific Tests & Remarks: 
  • Piezoelectric: develops an electric charge when pressure is applied.
  • Pyroelectricity: develops an electrical charge when heated.
  • Diasterism in star variety (star visible in reflected and transmitted light).
Synthesis: 
Hydrothermal process:
  • Identification: type of twinning, seed plate, breadcrumb inclusions, Raman / infra-red spectroscopy.
Simulants (with key separation tests): 
Scapolite (optic figure/sign, U.V. fluorescence, inclusions, doubling), synthetic amethyst (inclusions, infra-red spectroscopy), glass (optic character), iolite (optic figure, pleochroism), natural spinel (optic character).
Geological Occurrence: 
Very widespread, in pegmatite.
Sources: 
Brazil, India, South Africa, Namibia, Madagascar, Zambia, Sri Lanka.
Cuts & Uses: 
Facetted cuts, cabochon, carvings, beads, etc.

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Jewellery is one of the most bought products online. An estimated $1 billion USD of diamonds are bought annually via the Internet. Over 40 million people use the Internet to trade!

In Germany, the garland of ambers is hung around the necks of the infants, so that their teeth might come out without much trouble.

In Turkey, people fix a piece of amber in the hubble-bubble, dogged by an age old belief that the presence of the jewel would destroy all the germs and no disease would spread, even after many have dragged their puffs from it.

In Greece, people think if wine is poured into the cups made of amethyst, one does not get drunk after drinking that.

In Rome, a talisman having coral pieces is considered very auspicious to quell the bad spells of evil look. The Romans were in the habit of hanging chains made of ancient coral pieces from the cradle of the infants to protect them from evil effects.

In China, people wear rings studded with tiny conch or oyster shells as they believe it cures all aches such as stomach ache, worms and like.

In India, pendants made of silver and studded with pearls are hung from the necks of the children to save them from any bad effects.

Greeks still believe, if women wear blue sapphires then no sense of immorality would pollute their mind nor can any fear of the supernatural can trouble them.

The Pope Innocent III had circulated an order asking all the priests wear blue sapphire, so that morality can be strengthened.

It is said about turquoise, that when the stone changes its color into yellow, it actually signals bad times to the person who wears it.

It is believed that a turquoise gifted to a friend or a lover turns his or her life into one of happiness and good luck.

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