1.6" Extremely Fluorescent Hyalite Opal on Feldspar - Nambia

This is a gorgeous 1.6" wide hyalite opal on feldspar specimen, collected from Erongo Region of Namibia. Under both longwave and shortwave UV light, the hyalite opal exhibits a vibrant green fluorescence. The reaction to shortwave UV is a result of trace uranyl ions.

It has been mounted to an acrylic display base with mineral tack.

Hyalite is a transparent to translucent variety of opal that typically bears a globular structure. An amorphous form of silica (SiO2), hyalite opal forms as a volcanic sublimate in volcanic or pegmatic rock and is thereby considered a mineraloid. It can be referred to as water opal, jalite, or even Muller's glass, named after the man who discovered it, Franz-Joseph Müller von Reichenstein. It has a hardness of 5.5–6 on the Mohs scale and exhibits conchoidal fracturing.
Opal var. Hyalite & Feldspar
Erongo Region, Namibia
1.6" wide