Inorganic Gemstones

Garnet


Properties
Chemical Composition: 
Basic Formula: A3B2C3 where: A = Ca, Mn, Mg, Fe; B = Al, Fe, Ti, V, Cr; C = (SiO4)
Classification / Type: 
This is a major isomorphous group of gemstones. This group is divided into 2 sub-groups of 3 species each. Due to the strong isomorphism between species, a very high percentage of garnets are classified as Intermediate species.
  1. Pyralspite Series
    1. Pyrope: Mg3Al2(SiO4)3
    2. Almandine: Fe3Al2(SiO4)3
    3. Spessartite: Mn3Al2(SiO4)3
  2. Ugandrite Series
    1. Grossular: Ca3Al2(SiO4)3
    2. Andradite: Ca3Fe2(SiO4)3
    3. Uvarovite: Ca3Cr2(SiO4)3
Colors / Varieties: 
  • Idiochromatic Garnets
  • Allochromatic Garnets
    • Pyrope: Intense red color, orangish red, violet-red
    • Grossular: Orange to yellowish orange, reddish orange to brownish orange
    • Andradite (Demantoid): Green, yellowish-green
Crystal System / Forms: 
Cubic System / Dodecahedron, Trapezohedron or a combination of varying cubic forms.
Cleavage / Fracture: 
None but when present is imperfect and poor cleavage parallel to dodecahedral faces / Sub-conchoidal to uneven fracture
Optic Character: 
Isotropic; may exhibit A.D.R. reaction. Red, purplish red, brown and yellowish brown may show A.D.R. (S.R.) or a misguiding D.R. reaction.
Lustre: 
Vitreous to Adamantine
Pleochroism: 
Nil
Geological Occurrence: 
In metamorphic and igneous rocks; also as alluvial deposits. Also in kimberlite, peridotite, serpentine.
Cuts & Uses: 
Facetted, cabochon, beads, carvings, etc.

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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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