An opalized shell ?

[u/dewbijou]

I bought a jar of rocks from a thrift store and found this fossil inside. It looks normal when dry but when it gets wet, more is revealed!

What would be the best process of cleaning and polishing in order to enhance it? A series of sandpaper grits? Or should I keep it in a jar of water and just leave it alone?

[u/GeometreeOfLife]

Possibly agatized 🤷‍♂️ I would DEFINITELY not polish it, cuz you’ll lose the natural outer texture. That is an epic Goodwill find 👏

[u/deadmeat08 → u/GeometreeOfLife]

You could probably just do a quick little buff and polish with a Dremel polishing wheel. Start in a small, out of the way area to see if it changes anything.

[u/jaxinslacks]

Possibly agatized or opalized. Don’t polish it.

Leave this one as a specimen. Gorgeous piece!! You can do a specific gravity test to get close but it looks like there’s some sand inclusions so it may not be super accurate

[u/Totosh1o]

Just keep it in a jaw of water… and show us! Of course.

[u/dewbijou]

Thanks everyone-- I think consensus is I do not polish! I'll separate it from the rest of the rocks and keep it on display in it's special own container :)

[u/MrGiggles008 → u/dewbijou]

This is an awesome fossil. Glad you are leaving it unpolished. It will hold its value better as a fossil rather than a polished rock. If you want it to maintain the wetter look, you can use a paraloid b72 application on it (or something similar). This is something commonly used on fossils both for consolidation and giving it a finished appearance. It can help make it look wet and clearer, if that is desired.

[u/Guava-Jazzlike]

What a find! Keep it it the way it is!

[u/spider-season]

To make it look more like it does wet without polishing it, you can soak it in mineral oil then dry it.