sedimentary

Puddingstone

Conglomerate (Silicon Dioxide - SiO2 with various inclusions)

Hardness: 6.5-7 (Mohs); Color: Cream/white matrix with red, brown, and green clasts; Luster: Waxy to dull (polishes to vitreous); Crystal Structure: Hexagonal (cryptocrystalline matrix); Cleavage: None; Specific Gravity: 2.6-2.65

Hardness: 6
Color: Cream/white matrix with red, brown, and green clasts
Luster: Waxy to dull (polishes to vitreous)

Identified June 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed during the Neoproterozoic to Paleozoic eras. These rocks are conglomerates created when rounded pebbles (clasts) are cemented together in a fine-grained silty or sandy matrix, often later smoothed by glacial action.

Uses & applications

Used primarily for lapidary work, jewelry making (cabochons), as decorative garden stones, and as high-interest geological collector specimens.

Geological facts

The most famous variety is the 'Huron Puddingstone' from the Michigan/Ontario region, which was carried south from Canada by glaciers during the last Ice Age. Its name comes from its resemblance to a traditional boiled suet pudding with raisins and nuts.

Field identification & locations

Identify in the field by looking for distinct, colorful, well-rounded pebbles embedded in a lighter quartz-rich matrix. Often found in glacial till, on Great Lakes beaches, or in riverbeds. High quartz content makes it very durable.

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