Fluorescent Australian Hyalite Opal. This piece lights up well under short wave ultraviolet light. This is a superb Aussie fluoro specimen to grace your collection.
Squaretop Mountain, Queensland, Australia.
6.9cm x 3.5cm x 2.4cm, 43g.
Hyalite: SiO2 · nH2O.
A colourless variety of Opal. Hyalite is opal-AN, an amorphous silica glass containing about 3-8% water.
Because it has a different structure, it does not show the opalescence play of color that is found in precious opal.
Hyalite occurs as globular and botryoidal masses and irregular crusts in volcanic and pegmatite environments where the silica deposits from the gas phase. It often shows a strong green fluorescence in UV light.