2.5" Botryoidal Hyalite Opal with Chalcedony - Mexico

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.