"Store Didoni" Collection, Macherio (MB)

Typically found in Madagascar and Mexico, it is a variety of jasper characterized by circular or “orbicular” patterns (concentric eyes) resulting from the radial crystallization of silica around nucleation centers during the devitrification of volcanic ash or glass in underwater or lacustrine environments. Each “eye” forms through the spherical growth of chalcedony and quartz fibers starting from a central nucleus, often in the presence of geothermal fluids rich in coloring elements (iron, manganese). Hardness 6.5–7 on the Mohs scale, density 2.6 g/cm³.

A stone highly sought after by collectors and gem cutters for the uniqueness of its orbicular pattern, which differs in every specimen and is sometimes compared to lunar landscapes or the ocean floor; widely used for spheres, caskets, hearts, and fine carved objects; also valued in crystal therapy.