sedimentary
Puddingstone (Gowganda Tillite/Jasper Conglomerate)
Jasper Conglomerate (SiO2 primary composition)
Hardness: 6.5-7 (Mohs). Color: Tan/cream matrix with embedded red jasper clasts. Luster: Dull/waxy. Texture: Clastic/Coarse.
- Hardness
- 6
- Color
- Tan/cream matrix with embedded red jasper clasts
- Luster
- Dull/waxy
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Tan/cream matrix with embedded red jasper clasts. Luster: Dull/waxy. Texture: Clastic/Coarse.
Formation & geological history
Formed roughly 2.3 billion years ago during the Huronian glaciation. It is a lithified glacial till (tillite) where red jasper pebbles were trapped in a fine-grained sandy matrix.
Uses & applications
Used in ornamental stone carving, lapidary work (jewelry), and historical building material. Frequently collected as a decorative garden or shelf specimen.
Geological facts
The red clasts are typically jasper, while the creamy matrix is quartz sand. It was famously used to mark the 'original' location of Plymouth Rock by some mistaken historical accounts, and is the state rock of Michigan (unofficially) and common in Ontario.
Field identification & locations
Identify by looking for distinct bright red or dark brown rounded pebbles 'frozen' in a lighter, harder matrix that cannot be scratched by a steel knife. Found in Great Lakes glacial drift.
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