Puddingstone (Gowganda Tillite/Lorrain Quartzite)

Physical Properties

Hardness: 6.5-7 (Mohs), Color: Brownish-red to tan matrix with colorful rounded pebbles of red jasper, white quartz, and black chert. Luster: Dull matrix, vitreous pebbles. Structure: Clastic sedimentary.

Formation & Geological History

Formed roughly 2.2 to 2.4 billion years ago during the Paleoproterozoic era. It originated as river-deposited gravel and sand (Huronian Supergroup) that was eventually buried, compacted, and cemented into stone.

Uses & Applications

Primarily used for ornamental purposes, lapidary work (cabs, bookends), landscaping, and as a popular collector item.

Geological Facts

The 'Puddingstone' name comes from early British settlers who thought it looked like boiled suet pudding with raisins and fruit. It is functionally a glacial erratic in many locations, moved south by glaciers during the last Ice Age.

Field Identification & Locations

Identify by looking for distinct, colorful rounded jasper pebbles embedded in a hard, sandy quartz matrix. Commonly found in the St. Joseph Island area of Ontario and through the Great Lakes region, especially Michigan and Ohio.

Identified on: 5/18/2026

Mode: Standard