sedimentary

Jasper Conglomerate

Jasperoid Conglomerate (predominantly SiO2 with iron oxide impurities)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, gray, burgundy with darker clasts; Luster: Dull to waxy; Texture: Clastic with rounded grains; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Reddish-brown, gray, burgundy with darker clasts
Luster: Dull to waxy

Identified May 3, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, gray, burgundy with darker clasts; Luster: Dull to waxy; Texture: Clastic with rounded grains; Specific Gravity: 2.6-2.9

Formation & geological history

Formed through the lithification of rounded pebbles and sand in high-energy aquatic environments, such as riverbeds or coastal wave zones, followed by silica-rich cementation. Many such specimens date to the Proterozoic or Paleozoic eras.

Uses & applications

Used primarily as decorative garden stones, in lapidary work for cabochons, and as a collectible specimen for geological study.

Geological facts

Conglomerates like this are often referred to as 'puddingstones' if the contrast between the matrix and pebbles is high. The red color is typically due to hematite (iron oxide) staining within the jasper pebbles.

Field identification & locations

Identify in the field by looking for rounded pebbles (clasts) fused together by a finer-grained matrix. Found commonly in glacial till, old riverbeds, and near the Great Lakes region in North America.