sedimentary

Puddingstone

Conglomerate

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: Matrix is often light to dark brown or red with colorful rounded clasts of jasper/chert, Luster: Dull to waxy, Crystal Structure: Clastic

Hardness: 6
Luster: Dull to waxy, Crystal Structure: Clastic

Identified July 7, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Matrix is often light to dark brown or red with colorful rounded clasts of jasper/chert, Luster: Dull to waxy, Crystal Structure: Clastic

Formation & geological history

Formed during the Neoproterozoic or Paleozoic eras as river-borne gravel and pebbles were deposited and cemented together by a fine-grained silica-rich matrix over millions of years.

Uses & applications

Primarily used as a decorative stone, in landscaping, and in jewelry (as polished cabochons). Historically used for grinding grain and in building foundations.

Geological facts

The name comes from the stone's resemblance to a traditional English plum pudding. Michigan and Ontario puddingstones are famous for containing bright red jasper clasts.

Field identification & locations

Identify by looking for distinct, rounded, colorful stone 'plums' embedded in a solid matrix. Common in the Great Lakes region, particularly on St. Joseph Island and the Drummond Island area.