FMF - Friends of Minerals Forum, discussion and message board

[mholdgraf]

Does anyone know if Hardin County fluorites, particularly pale blue ones, tend to fade if exposed to direct sunlight?

[Jesse Fisher]

From my experience, Southern Illinois fluorites are pretty color-stable. For the final work, however, I would check with Ross Lillie (North Star Minerals) as he's been dealing in them for many years and likely knows more about the mines and minerals there than anyone else around.

[Jordi Fabre]

[alfredo]

Basically, any transparent mineral with a known chromophore element (emerald, ruby, jadeite, etc), I wouldn't hesitate to leave in sunlight. But when there is no known chromophore and the colour might be due to radiation, charge transfers, etc, I'd treat it as light sensitive until proven otherwise. Very imprecise and crude rule, I know, but it works for me.

[mholdgraf]

Thanks very much, everyone. I appreciate the info!