FMF - Friends of Minerals Forum, discussion and message board

[Screenname]

I only have this on one of my crystal specimens, I believe it is quartz but all these crystals look the same to me any how here are the pics. Any idea what it is, I think it makes the crystal look very pretty. I can't find anything like this on the web or in my books so I thought an expert might be able to help me. I apologize if this sounds like a dumb question but I can not find this any where and I can't figure out any explanation for it I am still new to this even though I have been reading up on the subject.

[alfredo]

Looks like amethyst from Brazil that has been baked to change the color from purple to yellow. They do that a lot over there to create "citrine".

[Jason]

you say "on the quartz" as on the outside? if so probably some iron type coating or staining

[Screenname]

[Luiz Menezes]

It looks to be a amethyst that was over-heated; I don't know details about the thermal treatment of amethyst to make it become yellow, but I know that if a critical temperature is exceeded the color changes to milky and the specimen turns opaque and worthless; it looks that the themal treatment was stopped just as this change to milky was starting to happen.

Luiz