Wednesday, October 9, 2013

Birthstones: Garnet (January)

garnet crystalsBy her who in [January] is born
No gem save garnets should be worn;
They will ensure her constancy,
True friendship, and fidelity.
January and garnet is one of the more consistent associations among birthstones. It appears in all three contemporary sources for birthstones: the Tiffany & Co. list, the Kansas City list, and the British Goldsmiths' list.

In particular, January is associated with red garnets. Garnet comes in a variety of colors, but it seems that despite the vague entreaty in the Tiffany & Co. poem above, January's stone has been a red garnet.

Garnet is another variety of silicate, meaning that at its core it contains silicon and oxygen (mostly oxygen). Specifically, it is a nesosilicate, which means that on a molecular level, garnet is a bunch of tetrahedrons (like a 4-sided die) connected to each other via single ions.

garnet chemistry molecules

However, garnet isn't a pure silicate. While it's mostly silicon and oxygen, it also contains (necessarily) other elements: magnesium and aluminum; iron and aluminum; manganese and aluminum; calcium and iron; calcium and aluminum; calcium and chromium. The chemical formula then looks something like this: 


where X is occupied by +2 cations and Y by +3 cations; one SiO4 molecule has a charge of –4, thus everything balances out.

The word garnet comes from Latin garanatus, or "seedlike." This was in reference to the similarity in color between red garnet and the seed-filled pomegranate fruit. In addition to its use in jewelry, garnet is often used as an abrasive in sand blasting; mixed with water to cut steel; and as water filtration sand. Garnet is also important in the science of geothermobarometry: describing the heat and pressure history of a rock (metamorphic or intrusive igneous). Garnets in a rock act something like a diary, maintaining the temperature and pressure the rock experienced in past ages.

Needless to say, it also is a stunning, vibrant red that makes for beautiful jewelry.

'Gorgeous Garnet' by Kokoba

A celebration of January's birthstone, red garnet!

Tiny Garnet Necklace in Ster...

Navette Ring, size 8, red ga...

Garnet Gemstone Tumbled . B...

SALE - Red Garnet Bead Mix -...


Light Garnet Red 10mm Round ...

Large Almandine Natural Garn...

Wire Wrapped Earrings with G...

Garnet faceted cabochon - 6 ...

Garnet Crystal Natural

Full 13" strand Mozambi...

SALE Gold Red Garnet Gemston...

Garnet Sterling Silver earri...

Hollywood Calling.....Jewelr...

Garnet Stone, Garnet Cabocho...

Andara Crystal Garnet Red Di...

No comments:

Post a Comment