Clear quartz sphere or polished quartz cabochon (tentative)

Colorless to very pale translucent/transparent, vitreous luster, smoothly polished and spherical. Quartz has Mohs hardness 7, no obvious cleavage, conchoidal fracture, trigonal crystal structure, and specific gravity about 2.65. The perfectly spherical shape indicates human shaping and polishing rather than a natural crystal form. Internal cloudy areas may be quartz inclusions, fractures, or bubbles; bubbles would favor glass.

Natural quartz forms in igneous, hydrothermal-vein, and metamorphic environments over a wide range of geological ages. A sphere such as this would have been cut and polished from quartz rough. If it is glass rather than quartz, it is a manufactured silica-based material and not a geological specimen.

Small quartz spheres and cabochons are used for jewelry, ornaments, mineral collections, meditation objects, and decorative carvings. Quartz is also important industrially in glassmaking, electronics, optics, abrasives, and engineered stone.

Quartz is one of Earth's most abundant minerals and is the principal component of many sands, quartzites, and felsic igneous rocks. Clear gem-quality quartz is commonly called rock crystal. A round shape alone does not indicate a natural crystal.

Identification is uncertain from this single photograph. Check with a loupe for rounded gas bubbles, which strongly suggest glass, versus angular fractures or mineral inclusions, which support quartz. Quartz should scratch ordinary window glass and should not be scratched by a steel knife; glass is usually scratched by hardened steel or a quartz point. A specific-gravity or refractive-index test provides better confirmation. Common quartz sources include Brazil, Madagascar, Arkansas, the Alps, and many hydrothermal districts worldwide.