sedimentary

Puddingstone (Quartzite Conglomerate with Jasper inclusions)

Metaconglomerate (Silicon Dioxide, SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: White, cream, or gray matrix with contrasting red jasper pebbles; Luster: Vitreous to dull; Crystal structure: Microcrystalline/Massive; Cleavage: None (conchoidal fracture).

Hardness: 7 (Mohs scale)
Luster: Vitreous to dull

Identified July 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the cementation of rounded pebbles (conglomerate) and subsequent low-grade metamorphism. The red inclusions are specifically Jasper. Many specimens found in the Great Lakes region date to the Huronian Supergroup of the Paleoproterozoic era, approximately 2.3 billion years ago.

Uses & applications

Used primarily as decorative lapidary material, jewelry (cabochons), paperweights, landscaping stones, and collected by rockhounds for its distinct appearance.

Geological facts

The rock gets its name because the dark red jasper pebbles resemble raisins or fruit in a boiled suet pudding. It was widely used as a 'marker stone' by early explorers in the St. Joseph Island area of Ontario.

Field identification & locations

Identify by looking for rounded red pebbles embedded in a hard, light-colored quartz or quartzite matrix. Common in glacial drift across Michigan and Ontario. It is much harder than common concrete and will scratch glass easily.