What are these weird rocks?
June 10, 2018 5:20 AM   Subscribe

I was at an estate sale and to bring my total up to the necessary amount to use a debit card, I grabbed these rocks. I'm dying to know what they are.

A couple of things that might be helpful in figuring out what these are:

1. The estate sale was in Wisconsin, but I think the people who owned the estate either traveled or were immigrants. There were lots of books with titles in a different language (it looked Asian to me) and other things in the house that looked like they came from Asia.

2. Whatever these rocks are, I doubt they're valuable or rare - I got a plastic shoebox-sized box full of them for $5. I know the people running the estate sale probably aren't professional geologists with a comprehensive knowledge of rocks, but the rocks don't seem to have been set apart or displayed as something important.

3. Some of the individual fans (I don't know what to call them...the individual projections) are over an inch in length. The rocks also have seashells embedded in them.

4. Each individual piece seems to consist of a large, flat layer, with fanlike projections on one or both sides.

Any ideas on what these things could be? Thanks!
posted by christinetheslp to Science & Nature (8 answers total)
Coral would be my guess.
posted by lobstah at 5:35 AM on June 10, 2018

Desert Rose, salt and sand.

Have a look.
posted by Dagobert at 5:36 AM on June 10, 2018 [14 favorites]

Yup, desert rose for sure.
posted by Too-Ticky at 5:38 AM on June 10, 2018 [5 favorites]

Rocks and fossils (and generally archaeological finds as well) lose their value when the provenance (where it is from) is no longer known.
posted by DoubleLune at 6:11 AM on June 10, 2018 [1 favorite]

the individual fans (I don't know what to call them...the individual projections)

Here is a pretty good visual guide to crystal habits, ie the different types of shapes that crystallizing minerals take. Yours has "Rosette or lenticular (ie lens shaped) crystals." You could call the individual projections crystals or plates.

Desert rose definitely seems right, but that's just a colloquial name for this formation which can be made of a couple different types of mineral.
posted by showbiz_liz at 6:54 AM on June 10, 2018 [1 favorite]

Yes, desert roses. When I was a kid, we lived in North Africa for a while because my father was building a liquid natural gas pipeline in Algeria. We would go into the interior of the Sahara desert and dig or uncover them and take the most beautiful home. They are indeed lovely, and you got some good-looking specimens, and now you have some idea of where they come from!
posted by seasparrow at 9:16 AM on June 10, 2018

Hey, great find, these guys are so cool. It's desert rose for sure! There are lots of different places you can find this stuff in the world- scroll to the bottom on Mindat to find some localities. If you look at enough pictures, you might be able to start guessing at a location, based on the color and texture of the sand embedded in your rocks. A couple of links on how they form. I wouldn't say they're worth a lot of money, but since they only form under certain conditions, collectors like them, and unique shapes or sizes of them would certainly be considered precious by some and sell for a lot of money.
posted by Secretariat at 9:21 AM on June 10, 2018

> lose their value when the provenance...

I sell minerals, fossils, etc semi-professionally. Those selenite formations would sell easily for $25-75.
posted by humboldt32 at 11:50 AM on June 10, 2018

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