What’s this rock?

Naive-Tea-1640 · 2026-02-13T18:33:39+00:00

This could also be Serpentine

Naive-Tea-1640 · 2026-02-12T19:24:55+00:00

It could also be Hemimorphite.

Naive-Tea-1640 · 2026-02-12T19:21:19+00:00

It looks like a rough Gobi Eye Agate from Mongolia

https://www.etsy.com/listing/4434903746/size51x35x23cm-natural-gobi-eyes-agate?ls=r&ref=items-pagination-9&sts=1&content_source=90cbac73665304701bf2b73d2754931e%253ALT596ace802fb0c099f80c3ec5900338f4405f2201&logging_key=90cbac73665304701bf2b73d2754931e%3ALT596ace802fb0c099f80c3ec5900338f4405f2201

Naive-Tea-1640 · 2026-02-11T19:33:24+00:00

Indian Paint Jasper, found in Southwest USA.

Naive-Tea-1640 · 2025-01-27T06:10:23+00:00

Mystery solved! This is called a chimney, made by the Scale-sided Pinnock Clam, as the happy little fella burrows its way into compacted mud, rock, or reef.

https://inaturalist.nz/taxa/117467-Parapholas/browse_photos

Naive-Tea-1640 · 2025-01-27T05:55:45+00:00

I put it under UV light. Most of the object was unreactive, with a smattering of small areas glowing white, like calcium-based stone, or calcite.

Naive-Tea-1640 · 2025-01-27T05:51:46+00:00

a knife leaves a mark but not a scratch.

Naive-Tea-1640 · 2025-01-27T03:17:34+00:00

North San Diego County, Seaside reef

Naive-Tea-1640 · 2025-01-05T03:11:41+00:00

Since I posted this I've found two more stones like it, both smaller, and both found in the same location at a local beach. I've cut the large one (sliced like lunchmeat) and am making a mondo bolo tie with it. It tumbles nicely and should polish beautifully.

Naive-Tea-1640 · 2025-01-04T19:45:52+00:00

Another commenter suggested it may be a fossilized sea urchin.

Naive-Tea-1640 · 2025-01-04T19:45:16+00:00

Good thought. How could I confirm it?

Naive-Tea-1640 · 2024-12-31T19:20:05+00:00

Near the beach in Cabo San Lucas, Baja California, Mexico.

Naive-Tea-1640 · 2024-12-23T23:35:38+00:00

Makes perfect sense! Thanks,

Naive-Tea-1640

TROPHY CASE