Andradite

Garnets containing titanium and manganese are grouped as andradite garnet. The most valuable is demantoid, whose emerald-green color is due to the presence of chromium. It has a higher dispersion than diamond and can be recognized by the characteristic "horsetails", which are fine, hair-like inclusions of asbestos. Topazolite, the yellow variety of andradite garnet, varies from pale to dark yellow. Only small crystals are found. Melanite is a generally black form, but can also be dark red.

The best demantoid is found in the Urals in Russia, and is associated with gold-bearing sands and metamorphic rocks. Other localities include northern Italy, Zaire, and Kenya. Topazolite crystals are found in the Swiss and Italian Alps in metamorphic rocks. Melanite is found in metamorphic rocks and volcanic lavas; fine crystals are found on the island of Elba (Italy), and in France and Germany.


Properties
Chemical Composition: 
Calcium Iron Silicate - Ca3Fe2(SiO4)3
Colors / Varieties: 
  • Demantoid: Green to yellowish green
  • Topazolite: Greenish yellow to yellow
  • Melanite: Black (opaque)
Hardness: 
6.5
Specific Gravity: 
3.70 - 4.10
Refractive Index / Birefringence: 
1.800 - 1.940
Dispersion: 
0.057
Magnification: 
  • Demantoid: Horse-tail pattern of byssolite / asbestos fibers, fingerprints.
  • Topazolite: Liquid and crystal inclusion.
U.V. Fluorescence: 
Inert
Spectrum: 
Demantoid: Strong band at 443nm (may appear as a cut off), 622nm & 640nm, 693nm & 701nm.
Cause of Color: 
  • Green: Chromium
  • Yellowish-green: Chromium, Iron
  • Black: Titanium, Iron
  • Yellow, brown: Iron
Treatment (Enhancement): 
-
Specific Tests & Remarks: 
-
Simulants (with key separation tests): 
Natural Zircon (optic character, spectrum, inclusions), Synthetic Cubic Zirconia (lustre, inclusions, spectrum), Y.A.G. (inclusions, spectrum, fire), Sphene (optic character, spectrum, fire doubling), Chrysoberyl (optic character, R.I., spectrum, inclusions, fire), Tourmaline (optic character, pleochroism, life, fire), etc.
Sources: 
Russia (Ural Mountains), Namibia, Pakistan, U.S.A. (California, Arizona)
Cuts & Uses: 
Facetted, cabochon, beads, carvings, etc.

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