Tumbled quartz-rich rock, possibly jasperized quartz or quartzite

Pale cream to white, rounded and water-worn or tumbled, with brown-red iron-oxide veins and patches and a small dark cavity. Likely vitreous to slightly waxy luster. Quartz has Mohs hardness 7, no cleavage, conchoidal fracture, and specific gravity about 2.65. The specimen appears massive rather than showing distinct crystals. A steel file should not scratch quartz, while quartz should scratch ordinary glass.

Probably formed from silica-rich rock that was metamorphosed or cemented, followed by fracturing and circulation of iron-bearing fluids that produced the reddish-brown staining. The rounded shape indicates stream transport, beach abrasion, or deliberate tumbling. Its geological age cannot be determined from the image; quartz-rich rocks range from Precambrian to relatively young formations.

Primarily a lapidary, decorative, or collection specimen. If the material is sufficiently uniform, it may be cut into cabochons or used for small carvings and tumbled stones. Quartzite is also used as crushed stone, aggregate, and building or paving stone, though this particular specimen is too small for construction use.

The reddish and brown coloration is most likely caused by hematite and limonite/goethite rather than by the main quartz mineral. The dark opening may be a vug or weathered inclusion. The image does not show enough diagnostic texture to distinguish confidently among quartzite, jasper, chalcedony-bearing rock, or a quartz-rich vein fragment.

In the field, test hardness first: a quartz-rich specimen resists scratching by a knife and scratches glass. Look for granular quartz texture, conchoidal fracture, lack of cleavage, and iron-oxide veins. Quartzite typically has interlocking quartz grains and breaks across grains; jasper is more opaque and microcrystalline, while chalcedony is commonly smoother and waxier. Common sources include quartz veins, metamorphic belts, gravel bars, and iron-stained silica-rich formations worldwide. A streak test on unglazed porcelain may leave little to no streak, although iron oxides can produce a reddish-brown streak.