Home

Peridot


Properties
Chemical Composition: 
Silicate of magnesium and iron where iron is generally 12% - 15%, Cr, Mn & Ni may also be present. (MgFe)2SiO4
Classification / Type: 
Mineralogically known as Olivine, peridot belongs to the isomorphous Forsterite (Mg) - Fayalite (Fe) series.
Colors / Varieties: 
  • Forsterite: green, pale lemon yellow.
  • Fayalite: green, brown, yellowish green, olive green.
Crystal System / Forms: 
Orthorhombic System / Striated prisms, rolled pebbles, crystals are rare.
Hardness: 
6.5 - 7 (Fayalite - Forsterite)
Specific Gravity: 
3.34
Cleavage / Fracture: 
Imperfect to weak / Conchoidal fracture.
Optic Character: 
Anisotropic, D.R.; Biaxial positive.
Lustre: 
Oily to vitreous.
Refractive Index / Birefringence: 
1.654 - 1.690 / 0.036. Range: 1.640 - 1.700
Pleochroism: 
Weak
Dispersion: 
0.020
Magnification: 
Lily pad inclusions are halos with a crystal (chromite or chrome spinel) at the centre, glass balls that look like bubbles (Hawaiian), rectangular biotite crystals, doubling.
U.V. Fluorescence: 
Inert
Spectrum: 
Bands at 493nm, 473nm & 453nm.
Cause of Color: 
Iron - due to ferrous iron (ideally 12% - 15%). Presence of chromium gives a brighter green.
Treatment (Enhancement): 
-
Specific Tests & Remarks: 
  • Doubling is seen.
  • Brittle stone.
  • Attacked by acids.
Synthesis: 
-
Simulants (with key separation tests): 
Sinhalite (pleochroism, spectrum), Diopside (R.I., spectrum), Tourmaline (optic figure, R.I., S.G., pleochroism), Apatite (R.I., birefringence, inclusions, spectrum), Fluorite (optic character), Glass (optic character), Synthetic Spinel Triplet (optic character, inclusions)
Geological Occurrence: 
Found in peridotites, in concentrations in basalt and ultrabasic rocks.
Sources: 
Hawaii, Zeberged (Egypt), Isle of St. John, Myanmar, Pakistan, Norway, Kenya, U.S.A. (California, New Mexico and Arizona).
Cuts & Uses: 
Facetted cut, cabochon, beads, carvings, etc.
  • Click to bookmark & share this webpage

Did you know?

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.

Poll