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Identity HelpBrazil. Bought from a seller on Instagram.

24th Aug 2022 14:55 UTCKaren Gemma Richards

Hello everyone, this is my first post on here. I have this Amethyst cluster from Brazil. I've identified Goethite inclusions but I'm really stumped on the gold glittery round blobs on the surface. Any help would be much appreciated. Thank you.

Questions Answered
Can it scratch glass? : Yes
Can you scratch it with your fingernail? : No
Is it light/heavy for the size? : Normal

24th Aug 2022 15:11 UTCKevin Conroy Manager

The blobs are also goethite, the crystals are microscopic. Please see:

https://www.mindat.org/gallery.php?frm_id=pager&cform_is_valid=1&min=198&loc=5528&u=&potd=&pco=&d=&showtype=1&phototype=0&checkall=1&filtmin=0&filtassoc=0&loctxt=&keywords=Goethite+&orderxby=1&submit_pager=Filter+Search

25th Aug 2022 04:43 UTCKaren Gemma Richards

Thank you for your help. I appreciate it.

24th Aug 2022 16:34 UTCAmir C. Akhavan Expert

The yellow-brown color is caused by goethite, as Kevin said.

But if you see glittery round blobs that sit on the surface (and only partially inside the crystal), the glittery stuff are tiny quartz crystals.

25th Aug 2022 04:45 UTCKaren Gemma Richards

Yes that's exactly how they are. Almost like drops of glitter blobs that are extremely sparkly. One of them you can see has partially formed inside and outside surface of the crystal. Thank you for you help.

25th Aug 2022 06:57 UTCAmir C. Akhavan Expert

The blobs are (hemi-)spheres that were once made of a radially grown mineral, probably fluorite or calcite. They got encrusted with small quartz crystals and then dissolved, and the interior of the hollow spheres was then filled with quartz. Often it is claimed that the spheres are cristobalite, but there is no evidence for that and hard to imagine how that would work, while fluorite balls on amethyst are well documented from that area.

I'm working on a little article about them and a friend of mine tried some Raman measurements, but all he could see in the blobs was quartz. But I haven't cut fully embedded spheres open yet.

26th Aug 2022 16:53 UTCKaren Gemma Richards

That's fascinating thank you. I will post better pics once I get my dlsr out. They really are beautiful little blobs of gold glitter. The seller said they were Hematite but I knew it wasn't.