1.4" Polished Fire Agate - Calvillo Mines, Mexico

This is an authentic, 1.4" wide polished fire agate specimen collected from the Calvillo Mines of Aguascalientes, Mexico. The agate displays a gorgeous iridescent effect when rotated under a light source.

Fire agate is a variety of chalcedony that often displays a metallic, shimmering iridescence known as the Schiller Effect. It's believed to form by means of evaporation of fluids within a cavity that is already experiencing chalcedony deposition. In these cases, a thin iridescent film floating on the stagnant, silica-rich fluids forms as ferrous iron oxidizes when coming in contact with air in the cavity, producing ferric iron (Fe202). Once the cavity experiences a dry period, the thin iridescent film collapses onto the pre-existing chalcedony, depositing the iridescent layer that creates the fire effect. A following chalcedony band will enclose the iridescent film inside the agate. This process can repeat over multiple periods of hydration and dehydration of the pocket.

Chalcedony var. Fire Agate
Calvillo Mines, Calvillo, Calvillo Municipality, Aguascalientes, Mexico
1.4 x 1"