RocksdayAgate vs Turritella Agate
The quickest way to tell Agate from Turritella Agate: Turritella Agate is a fossil; Agate is a single mineral.
Banded chalcedony — quartz made of microscopic crystals — that fills cavities in volcanic rock layer by layer. Light passes through the bands when held up to the sun.
Photo: James St. John, CC BY 2.0
Chalcedony crowded with fossil freshwater snails. The shells are Elimia tenera; Turritella is a trade name that stuck.
Photo: Agiyo, CC BY-SA 4.0
Quick tests
- Texture: Turritella Agate is a fossil; Agate is a single mineral.
Key differences
- Agate is banded chalcedony without snail shells.
Side by side
| Property | Agate | Turritella Agate |
|---|---|---|
| Type | Mineral | Fossil |
| Mohs hardness | 6.5–7 | 6.5–7 |
| Luster | Waxy to vitreous | Waxy |
| Streak | White | — |
| Colors | Red, Orange, White, Gray, Brown, Blue | Brown, Black, White, Gray |
| Crystal system / structure | Microcrystalline quartz (chalcedony) | Snail shells in chalcedony |
| Specific gravity | 2.58–2.64 | 2.6–2.7 |
| Formula | SiO₂ | — |
| Found in | Lake Superior shores; Rio Grande do Sul, Brazil | Green River Formation, Wyoming |
Properties that are the same for both are grayed out.
How to identify agate
- Concentric or parallel bands, often in red, orange and white.
- Translucent at the edges when backlit.
- Waxy surface on rough, weathered pieces ('pitted' rind).
- Hard enough to scratch glass.
Crystal system: Microcrystalline quartz (chalcedony)
Full Agate guide →How to identify turritella agate
- Brown or black pointed snail shells packed in a hard silica rock.
- Scratches glass. Does not fizz.
- Polished slices show dozens of shells in cross-section.
Structure: Snail shells in chalcedony
Full Turritella Agate guide →More comparisons
Frequently asked questions
What is the difference between agate and turritella agate?
Agate is a mineral (SiO₂) with a Mohs hardness of 6.5–7 and a waxy to vitreous luster, usually red, orange, white, gray, brown or blue. Turritella Agate is a fossil with a Mohs hardness of about 6.5–7 and a waxy luster, usually brown, black, white or gray.
How can you tell agate from turritella agate?
Turritella Agate is a fossil; Agate is a single mineral. Agate is banded chalcedony without snail shells.
Could you tell them apart from a blurry close-up?
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