mineral

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, reddish, cream, and gray coloration with waxy to dull luster and no visible cleavage. Its rounded shape and glossy surface indicate natural water-wear or tumbling; exact identification is limited by the image.

Identified August 23, 2026More mineral →

Explore Tumbled jasper or chert 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

Silica-rich groundwater replaced or cemented sediment, commonly incorporating iron oxides that create the brown-red colors. Such material typically formed in sedimentary or volcanic environments, ranging from Paleozoic to recent deposits.

Uses & applications

Used as lapidary material for cabochons, beads, carvings, and tumbled stones; occasionally used decoratively. Common pieces have modest commercial value.

Geological facts

Jasper is opaque microcrystalline quartz, while chalcedony is generally translucent; both may occur together in brecciated or banded material. Iron staining commonly produces the rusty orange and brown tones visible here.

Field identification & locations

Look for a glass-scratching hardness, waxy surface, irregular mottling, and absence of cleavage; it should not fizz in dilute hydrochloric acid. Common sources include river gravels and volcanic-silica deposits worldwide.