sedimentary
Gowganda Tillite (Puddingstone)
Glacial Tillite (Diamictite) with Jasper inclusions
Hardness: 6.5-7 (Mohs); Color: White to grey matrix with red jasper clasts; Luster: Dull to waxy; Structure: Conglomerate/Breccia; Cleavage: None
- Hardness
- 6
- Color
- White to grey matrix with red jasper clasts
- Luster
- Dull to waxy
Identified More sedimentary →
Explore Gowganda Tillite (Puddingstone) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs); Color: White to grey matrix with red jasper clasts; Luster: Dull to waxy; Structure: Conglomerate/Breccia; Cleavage: None
Formation & geological history
Formed during the Huronian glaciation approximately 2.2 to 2.4 billion years ago. It is a lithified glacial deposit where rocks were trapped in ice and later settled into a fine-grained silty matrix.
Uses & applications
Primarily used as a lapidary material for jewelry, paperweights, and decorative ornaments. Historically used in localized construction but now a popular collector's item.
Geological facts
This specific variety is often called 'Michigan Puddingstone' or 'St. Joseph Island Puddingstone'. It is one of the oldest known glacial deposits on Earth, marking a 'Snowball Earth' period.
Field identification & locations
Identify by looking for distinct bright red jasper 'plums' embedded in a harder, lighter-colored quartz or siltstone matrix. Common in the Great Lakes region, especially Michigan and Ontario.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary