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Rock Art => Cabochons, Intarsias, Cameos => Topic started by: R.U. Sirius on September 22, 2025, 11:00:59 AM

Title: Red horn coral
Post by: R.U. Sirius on September 22, 2025, 11:00:59 AM

Here is a high-dome cab, along with a finger-tip sized piece of rough similar to the one that got cabbed. I believe this is an agatized red horn coral from Utah.

I was hoping for a more pronounced starburst pattern looking from top, but overall turned out nice, and took a decent shine with very little effort (skipped from worn 800 SiC straight to cerium oxide).

Title: Re: Red horn coral
Post by: lithicbeads on September 24, 2025, 05:12:37 PM

Very nice. I recently bought a few pieces of golden coral which is new to me.   

Title: Re: Red horn coral
Post by: R.U. Sirius on October 07, 2025, 01:36:38 PM

Quote from: lithicbeads on September 24, 2025, 05:12:37 PM

Very nice. I recently bought a few pieces of golden coral which is new to me.

The golden coral I've seen was actually one of the black coral species, treated with hydrogen peroxide to oxidize the surface to a golden sheen.

If that's what your material is, keep in mind that the golden color might not run deep, and also that it is neither a carbonate nor agate, but protein - treat it more like antler than a stone. I've cut some Maui black coral pieces... started with 280 soft wheel, and after 600 and 800 finished it off with zam to a surprising shine. Beware of heat.

Title: Re: Red horn coral
Post by: auscarver on October 17, 2025, 03:40:51 PM

Nice. Coral. I like the colour. Did it need sealing. Good polish.

Title: Re: Red horn coral
Post by: R.U. Sirius on October 21, 2025, 10:38:47 PM

No sealing, no treatment of any kind. You'll notice the rind is very rough, but there are no vugs nor cracks once you remove the outer mm or so.