Encapsulated in the interior of these glass spheres are salt pellets, which are the remains from the explosive chemical process that created them. When ceramics salts are trapped in molten glass, the heated salts release gas fumes that pressurize the solid glass and force it into a bubble. The sparkling metallic residue on the black spheres is produced by smoke trapped on their interior walls. Transparent forms result when the spheres are not fully enclosed; chemicals escape, leaving a subtle crystalline dust.
