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Grossular Garnet Gemstone Information

Grossular from the Latin name for 'Gooseberry' refers to the green coloured gemstone, it also occurs in yellow, orange and brown colours. Grossular is a species of garnet with the following varieties:

Hessonite: A red to orange to yellow variety, with a brownish tint, some are described as a cinnamon colour. Hessonite is cut as faceted stones and cabochons for use in jewellery making.

Source locations include: Brazil, Canada, India, Madagascar, Sri Lanka, Tanzania and USA.

Tsavorite: A yellow-green to grass green variety. The grass green variety is prized for its rarity and a colour that resembles emerald, in good quality stones. Gem grade facet-cut tsavorite can fetch high prices, included stones are cut en cabochon.

Source locations include: Africa (Kenya-Tanzania border and also in Tunduru, South Tanzania) and Madagascar.

Hydrogrossular: Is a massive form of garnet found in brown, pink and green colours. It is translucent to opaque and is used to make carvings and jewellery. Hydrogrossular is very similar in appearance to nephrite jade and some gem markets refer to it as Transvaal Jade or Garnet Jade. The green coloured stone is popular for that reason and is probably sold as jade in some makets.

Source locations include: South Africa, Myanmar (formerly Burma) and Zambia.

Leuco garnet: A colourless variety of Grossular Garnet rarely found. They are often not totally colourless but may have a slight colour tinge. Their bright vitreous lustre and a high refractive index allow faceted stones to deliver very good brilliance, when cut correctly.

Source locations include: Mexico and Tanzania.

Physical Properties

Stone type:
Grossular is a species the garnet group.
Crystal System:
Cubic (isometric).
Chemical Composition:
Calcium aluminium silicate, Ca3AI2(Si04)3.
Colour:
As above for each variety.
Lustre:
Bright vitreous.
Pleochroism:
Absent.
Dispersion:
Medium.
Hardness:
7¼ on the Mohs' scale of hardness.
Toughness:
Good.
Cleavage:
None.
Density in gm/cc:
3.4 to 3.8
Double refraction:
None.
Refractive index:
1.73 to 1.75

Common Treatments

Grossular garnet is not normally treated.