mineral

Tumbled jasper/chalcedony pebbles

Microcrystalline quartz (SiO₂), likely jasper and brown chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; opaque to slightly translucent, brown, tan, reddish, and gray colors; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage. The polished pieces show conchoidal fractures and possible iron-oxide staining.

Identified August 26, 2026More mineral →

Explore Tumbled jasper/chalcedony pebbles in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed when silica-rich groundwater filled cavities or replaced volcanic and sedimentary material, commonly during volcanic or weathering processes. Exact geological age and locality cannot be determined from the image.

Uses & applications

Used as inexpensive lapidary material for cabochons, beads, carvings, and decorative stones; also collected as polished specimens.

Geological facts

Jasper is opaque and commonly colored by hematite or goethite, while chalcedony is more translucent. The assortment may include unrelated river pebbles, so exact identification requires locality and testing.

Field identification & locations

Identify by its very high polish, glassy or waxy surface, lack of cleavage, and ability to scratch ordinary glass. Common sources include volcanic terrains, river gravels, Brazil, India, Madagascar, and the western United States.