Facts about Garnet Garnet is the name given to a group of
complex silicate minerals with a similar chemical formula,
similar physical properties and a common crystal system. Five of
these minerals, almandine, pyrope, spessartine, grossular and
andradite, are used as gemstones. Garnet forms in the cubic
system and is common in Australian metamorphic rocks. Localities
for gem quality garnets are more restricted. - Chemistry:
Aluminium silicate - Hardness: 6.5 - 7.5 - Refractive Indices:
1.730 - 1.888 - Specific gravity: 3.65 - 4.20 - Lustre: vitreous
Grossular garnet is found in the Harts Range, Northern
Territory. here it occurs in its pure, colourless form and with
the addition of iron to colour it yellow, orange and red. The
yellow and orange colours are known as hessonite garnets. New
South Wales The red pyrope-almandine series of garnets, in which
one type gradually changes into the other, is found at many
Australian gem localities. Almandine is the iron-rich end
member, while pyrope is magnesium rich. An