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Let's Rock => Identifications of Materials => Topic started by: AlexR on May 17, 2018, 12:33:42 PM

Title: Quartz? quartzite?
Post by: AlexR on May 17, 2018, 12:33:42 PM

Hello to all gemologists, hi guys,
I have this gem stone and I would like to know what is it. A kind of quartz? its hard, about 6 or 7 moohs
Any ideas?

Thank you

Title: Re: Quartz? quartzite?
Post by: ileney on May 17, 2018, 01:55:25 PM

What we used to call Mexican onyx (calcite, travertine), maybe?

Title: Re: Quartz? quartzite?
Post by: AlexR on May 17, 2018, 02:14:26 PM

Great! You are quite right. I just found photos of Mexican onyx. Thank you!

Title: Re: Quartz? quartzite?
Post by: Jhon P on May 17, 2018, 08:39:06 PM

Calcite oynx is only a hardness of 3 to 4 if your stone is a 6 or 7 it’s not calcite oynx

Title: Re: Quartz? quartzite?
Post by: AlexR on May 23, 2018, 09:47:37 AM

Hi Jhon P, hi guys,
Yes, may be. But it looks very similar.

I have found a nice piece, is it the same kind or different? Please help to identify. Thank you.

Title: Re: Quartz? quartzite?
Post by: Jhon P on May 23, 2018, 10:17:36 AM

It sure looks like oynx but if it a 6 or 7 it has to be agate. Try scratching it with a pocket knife oynx will make a deep scratch

Title: Re: Quartz? quartzite?
Post by: AlexR on May 23, 2018, 10:33:09 AM

The scratch is light. I cannot make deep scratch with a knife. So it is agate(?)
Thank you.

Title: Re: Quartz? quartzite?
Post by: ileney on May 23, 2018, 11:12:14 AM

I really think it's onyx. I suspect the knife isn't sharp or isn't stainless steel.  (But I could of course be wrong.)

Title: Re: Quartz? quartzite?
Post by: AlexR on May 23, 2018, 11:27:38 AM

It's easy to scratch. The knife is sharp and probably stainless steel (Swiss military 25-tool knife ). Yes, probably you are right, guys. It's onyx.

Title: Re: Quartz? quartzite?
Post by: Jhon P on May 23, 2018, 12:49:31 PM

I have a ton of calcite oynx I make spheres out of. If it’s agate you may be leaving a mark and not a scratch. Leaving a little metal on the stone. Steel is about a 5 1/2 calcite oynx is 4, I think some can be up to 5.
Do you have a piece of quartz, agate, or jasper? Try scratching it with that