Garnets can vary from pink, through red, to orange, yellow, green and black. Recent finds have now added blue to the myriad of colours. So for someone with a birthday in January the choice of colour and colour combinations is vast.
I deliberately headed this blog with a green Mali Garnet to prove the point that the birthstone for January does not have to be red.
But what is Garnet?
What is its scientific nature?
What is its otherworld properties?
Garnets are a very complex group of gemstones.
They are an Isomorphous series, ie they have the same crystal structure, cubic, but with varying chemical mix.
This continuous blend can, for example, create a mid way garnet type. For example the popular Rhodolite garnet above is a Pyrope-Almandine mix.
Garnets can appear as inclusions inside other gemstones, for example as in the image of a diamond below.
Most of the more common Garnets fall into two groups: Pyralspites and Ugrandites. Pyralspites are the aluminum Garnets and Ugrandites are the calcium Garnets.
Pyralspite Garnet Group: The Pyralspites include Pyrope, Almandine and Spessartine. The name Pyralspite comes from Pyrope, Almandine, Spessartite. This includes the vast majority of gemstone garnets. There is a complete solid solution series between Pyrope, Almandine and Spessartine. These Garnets are often mixed. Malaia is a Pyrope-Spessartine mix and Rhodolite is a Pyrope-Almandine mixture.
Ugrandite Garnet Group: The Garnets with the widest color range fall into the Ugrandite Garnet Group. are the calcium Garnets.The Ugrandites include Uvarovite, Grossular and Andradite. The name Ungrandite comes from Uvarovite, Grossular and Andradite. There is a complete solid solution series between Uvarovite, Grossular and Andradite. As with Pyralspites these Garnets are often mixed. Grandite (or Mali Garnet) is a mixture of Grossular and Andradite.
Garnet Physical Properties: General garnet composition: A3B2(SiO4)3, where Ca, Mg, Fe2+, or Mn2+ occupy the A site, and the B site contains Al, Fe3+ or Cr3+. Hydrous garnets may contain up to 8.5% H2O.
Pyralspite Garnet Group
Ugrandite Garnet Group
There are far less common types, which are rarely if ever found in jewellery. There are even garnets from space, such as Majorite which was discovered in a meteorite.
With such a wide diversity in chemical composition other properties such as hardness are varied. The benchmark for hardness is MOHS scale. With Talc at 1 as the softest and Diamond at 10 as the hardest. The scale is (1) Talc, (2) Gypsum, (3) Calcite, (4) Fluorspar, (5) Apatite, (6) Orthoclase feldspar, (7) Quartz, (8) Topaz, (9) Corundum, (10) Diamond.
The most common Garnets have a hardness rating as follows: Almandine (7.5), Andradite (6.5), Grossular (7.0 – 7.5), Pyrope (7.25), Spessartite (7.25), Uvaroite (7.5).
If you are interested in the science of gemmology I can no more than suggest you attend some of the wonderful courses run by the Gemmological Association of Great Britain www.gem-a.com
THE OTHERWORLD PROPERTIES
Also associated with red garnets, in ancient times it was believed to remove anger.
George Frederick Kunz noted this in his wonderful book ‘The Curious Lore of Precious Stones’ (1913) that ‘the symbolism of color played a very important part in recommending the use of particular stones for special diseases’.