FMF - Friends of Minerals Forum, discussion and message board

[Clifford Trebilcock]

Hi Peter,

I have been following this topic with great interest. Lots of nice photos and detailed information. I have collected very similar Hyalite Opal specimens from the Consolidated Quarries here in Topsham, Maine. The Hyalite Opal coating is not quite as thick as the specimens you show from Mexico, but reacts exactly the same as the specimens from Mexico. I just assumed the Hyalite contained enough Autunite inclusions to fluoresce and give it the yellow/green color from the UV in the sunlight. I picked up several specimens without the use of UV light, and noticed the color was very hard to see in incandescent light but never paid much attention. Thin coatings of Hyalite Opal are pretty common in Maine pegmatites. Most is white or colorless and very hard to spot without a UV light. Some Hyalite Opal takes on a blue color with UV fluorescence decreasing as the blue color increases. I would guess trace amounts of copper are responsible for this material.

Cliff

[jorgedavid]