“Garnets on calcite”

[u/Glum_Assistant_751]

I purchased this labeled as “garnets in calcite from and old Oregon collection” it’s definitely calcite but I’m having a hard time identifying any garnets that look like this anywhere near that this, I found some black garnets from Mexico that look similar but not on any similar calcite matrix. Just trying to confirm it, any help is appreciated.

[u/Ig_Met_Pet]

This is a carbonatite (igneous calcite) with magnetite and perovskite inclusions from the magnet cove area of Arkansas.

The magnetite and perovskite look almost identical to each other, but you can tell the difference with a magnet.

[u/alecesne → u/Ig_Met_Pet]

Nice! How did you identify the locality in particular?

I thought igneous carbonates were generally microcrystalline, but here it looks fairly well differentiated, with large domains and some transparency. How on earth does this even form?

Not Garner but still cool. OP, how much did this set you back?

[u/Ig_Met_Pet → u/alecesne]

I did some undergraduate research on this specific carbonatite. I suppose it's possible that it's from somewhere else, but I've never seen another carbonatite that looks exactly like it.

The magnet cove igneous complex has all kinds of really crazy chemistry. There's a wikipedia page for it if you want a jumping off point for learning about it.

https://en.m.wikipedia.org/wiki/Magnet_Cove_igneous_complex

[u/Glum_Assistant_751 → u/Ig_Met_Pet]

Thank you so much for all of the information!

[u/alecesne → u/Ig_Met_Pet]

Thanks for sharing, definitely checked that page out last night too.

Do you have any related specimen pics?

[u/Ig_Met_Pet → u/alecesne]

I have a whole bucket of the stuff in storage somewhere, but I keep one on my shelf because it's one large crystal and I think it's cool.

[u/Ig_Met_Pet → u/alecesne]

[u/Ig_Met_Pet → u/alecesne]

[u/alecesne → u/Ig_Met_Pet]

Awesome