RocksdayCoprolite vs Shale
To tell Coprolite from Shale: Shale is a flat rock, not a discrete pellet or spiral.
Fossil feces. Many are phosphatic, nodular and keep a spiral or lumpy shape.
Photo: James St. John, CC BY 2.0
Compacted mud and clay that splits into thin layers. The most common sedimentary rock.
Photo: James St. John, CC BY 2.0
Key differences
- Shale is a flat rock, not a discrete pellet or spiral.
Side by side
| Property | Coprolite | Shale |
|---|---|---|
| Type | Fossil | Sedimentary rock |
| Mohs hardness | 3–4 | 3 |
| Luster | Dull | Dull |
| Colors | Brown, Gray, Black, Green | Gray, Black, Red, Green |
| Crystal system / structure | Phosphatic fossil dung | Clastic, very fine, splits in layers |
| Specific gravity | 2.5–3.2 | 2.4–2.8 |
| Found in | Lyme Regis, England; South Carolina | Burgess Shale, British Columbia; Marcellus, Pennsylvania |
Properties that are the same for both are grayed out.
How to identify coprolite
- A lump, spiral or segmented nodule that isn't a shell.
- Often brown or black, sometimes with bone or scale fragments.
- Heavier than a similar piece of shale.
Structure: Phosphatic fossil dung
Full Coprolite guide →How to identify shale
- Splits into thin, flat flakes along its layers.
- Grains too small to see.
- Smells earthy when wet.
- Soft and crumbly at edges.
Structure: Clastic, very fine, splits in layers
Full Shale guide →More comparisons
Frequently asked questions
What is the difference between coprolite and shale?
Coprolite is a fossil with a Mohs hardness of about 3–4 and a dull luster, usually brown, gray, black or green. Shale is a sedimentary rock with a Mohs hardness of about 3 and a dull luster, usually gray, black, red or green.
How can you tell coprolite from shale?
Shale is a flat rock, not a discrete pellet or spiral.
Could you tell them apart from a blurry close-up?
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