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For serious rockhounds, amateur fossil hunters,
gem queens & More!

Located in historic downtown San Juan Bautista, California
209 Third Street, 95045     (831) 623-4441

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October Rock
The Month

Black Onyx

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For more

"Rock & Fossils
of The Month"

Click on Seymore Rock!

"Black, Black, Black is the color of my true love's hair" are the words of the song and Black Onyx is the Rock of the Month for October! Onyx comes from the Greek word for “fingernail”. According to legend, Cupid trimmed the nails of the Goddess Venus while she was asleep. The Fates heard this, they turned the clippings to stone to prevent any part of the beautiful Venus from dying. Isn’t that a wonderful legend!

Onyx is a microcrystalline quartz known as chalcedony. It frequently forms gas cavities found in lava. Chemically, it SiO2. It’s pretty durable with a MOHs hardness of 7 on a scale of 10.

Natural Black Onyx is rarely pure black but rather banded. The solid black color is usually created using a very stable dying process which is completely accepted by the gemstone trade. Treatments for producing black and other colors include soaking or boiling chalcedony in a sugar solution and following that with a treatment with either sulfuric or hydroclholoric. acid. This acid treatment carbonizes the sugars. These techniques have been used since the Roman times and most so-called "black onyx" sold is artificially treated.

Black onyx has been used in jewelry and carving for centuries. In jewelry it is found in cabochons or as beads. Onyx has also been used to make bowls, pottery items, and decorative carvings.


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