Tumbled jasper or chert

Opaque, rounded and polished, with ochre-brown, tan, gray, and cream mottling; vitreous to waxy luster. Mohs hardness ~6.5–7, no cleavage, conchoidal fracture, specific gravity ~2.6. Exact variety is uncertain from the photograph.

Forms when silica-rich fluids replace or cement sediment, commonly with iron-oxide staining producing the brown-orange colors. Chert and jasper are generally Paleozoic to Cenozoic, depending on the host formation.

Used as decorative stone, cabochons, beads, carvings, and lapidary material; too small for construction use. Common tumbled pieces typically have modest collector value.

The irregular internal patterns resemble jasper, but polished chert, petrified wood, or even a highly altered volcanic rock can look similar. The specimen appears human-tumbled or polished.

Likely identifiable by its glassy conchoidal fracture and inability to scratch with a steel knife; it should scratch glass, while quartz or a steel file should not scratch it. Brown coloration commonly reflects hematite or goethite. Chert/jasper is plausible near the Sacramento–Placer region, though the exact locality cannot be determined visually.