Cantera Opal : What is Cantera Opal ? How Cantera Opal is formed ?

Pinfire Pattern Cantera Opal.
Pinfire Pattern Cantera Opal. Photo Copyright © Craig Gower

What is Cantera Opal ?

Cantera opal is a type of Fire opals that do not show play of color are sometimes referred to as jelly opals. Cantera means “quarry,” and such stones come from quarries at Magdalena, Queretaro and possibly other Mexican locations. Mexican opals are sometimes cut in their rhyolitic host material if it is hard enough to allow cutting and polishing. This type of Mexican opal is referred to as a Cantera opal. Also, a type of opal from Mexico, referred to as Mexican water opal, is a colorless opal which exhibits either a bluish or golden internal sheen.

How is Opal Formed?

Opal is formed by a silicon dioxide and water solution. When water runs down the earth, it takes silica from sandstone and brings it into cracks and voids, created by natural faults or decomposing fossils. This leaves behind a layer of silica as the water evaporates.

How Cantera Opal is formed ?

Cantera Opal is a gemstone formed from the “Rhyolite”. Rhyolite is a kind of “Igneous Rock”

These are only found in Mexico and type the same as the Australian boulder opals, but the host rock is ryolite rather than ironstone.

Where are Mexican fire opals mined?

Mexican opal is mined in the Mexican states of Queretaro, Hidalgo, Guerrero, Michoacan, Julisio, Chihuahua and San Luis Potosi.