Garnet is a fairly common gemstone found all across the globe. It has several different variants from grossular, the most common, to almadine, to spessartine, to andradite and a few more. I've written about the andradite garnet species before, but never specifically about the rainbow garnet variety. So, here we go!
In the andradite garnet family there are 4 variations, normal andradite which are a reddish/brown, melanite which are jet black, topazolite which are yellow and demantoid which are green. The rainbow garnet is a normal calcium & iron reddish/brown andradite with a special twist, it has iridescence which produces a rainbow of colors.
The coloring comes from water inclusions in-between crystal layers as the garnet formed.
Not much is actually known about the process of forming the iridescence still, but people are studying it.
Rainbow garnets primarily come from a small zone in a skarn deposit in Tenkawa Village, Nara-ken, Japan. Skarns are rocks that have been hydrothermally altered to form different minerals, usually high in concentrations of calcium, iron, magnesium, manganese and aluminum, which are prime garnet ingredients. Outside of the small zone that the rainbow garnets were found the andradites in the skarn deposit don't have iridescence.
There are a few other places in the world where andradite deposits produce rainbow garnets, like Bouse, Arizona, but those localities produce only a handful of the stones. Tenkawa produced a large quantity and all of the finest specimens have come from Tenkawa.
The man who discovered the deposit is Joji Sugimori. I know Joji personally and buy some of my better specimens from him. He dug out about a 10 feet deep hole from the skarn that was filled with garnets. As the deposit became known to other collectors many people also started digging. Unfortunately this caught the ire of locals and the village prohibited any further collecting at the site. So most of the rainbow garnets nowadays either come from Joji or are stones that have already been released from his stock or the few other collectors over the years.
(A faceted specimen I got from Joji two years ago)
If you are interested in having your own rainbow garnet I still have some left on my shop: https://www.etsy.com/shop/Rt395Minerals
I usually have the best prices on Etsy because I have no middle man. I get them straight from Japan. I hope to be getting some faceted pieces in March or April when I meet Joji again. Until then, thanks for reading!
Oh wow, the specimens are already in people's carts on Etsy.
!discovery 31
Ya, and there they sit.... I think Etsy is secretly doing that.
Bummer. Thought you had a number of interested buyers.
There are, they are probably just waiting for me to run a sale.
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Wow! I've never seen anything like those!
Some are really incredible. I sometimes wish I didn't sell the nicer ones! I always forget to get one for my collection.
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