Tumbled yellow jasper

Opaque mustard-yellow to brown, smooth water-worn/tumbled surface, dull to silky luster, cryptocrystalline quartz; Mohs hardness about 6.5–7, no visible cleavage, specific gravity roughly 2.5–2.7.

Forms when silica-rich fluids cement or replace sediment and volcanic material, with iron oxides producing the yellow coloration; commonly Precambrian to younger, but the specimen’s age cannot be determined from the image.

Used as an ornamental stone, cabochons, beads, carvings, and lapidary material; attractive polished pieces are collected but generally inexpensive.

Jasper is an opaque variety of chalcedony or microcrystalline quartz, and its colors commonly reflect hematite or goethite impurities.

Identify it by its opacity, fine-grained texture, waxy-to-dull luster, lack of cleavage, and hardness sufficient to scratch ordinary glass. Yellow jasper occurs worldwide, including India, Madagascar, Brazil, Australia, and the western United States; this appears naturally water-worn or tumbled.