RocksdayPetrified Wood vs Turritella Agate
To tell Petrified Wood from Turritella Agate: Petrified wood shows grain and growth rings, not spiral shells.
Ancient wood whose cells were replaced, one by one, with quartz — turning a tree into stone.
Photo: Michael Gäbler, CC BY 3.0
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
Key differences
- Petrified wood shows grain and growth rings, not spiral shells.
Side by side
| Property | Petrified Wood | Turritella Agate |
|---|---|---|
| Type | Fossil | Fossil |
| Mohs hardness | 6.5–7 | 6.5–7 |
| Luster | Waxy to vitreous | Waxy |
| Colors | Brown, Red, Yellow, Gray, Black | Brown, Black, White, Gray |
| Crystal system / structure | Wood replaced by silica | Snail shells in chalcedony |
| Specific gravity | 2.6–2.9 | 2.6–2.7 |
| Found in | Petrified Forest, Arizona; Ginkgo Petrified Forest, Washington | Green River Formation, Wyoming |
Properties that are the same for both are grayed out.
How to identify petrified wood
- Visible bark texture, growth rings or wood grain.
- Heavy and hard like agate.
- Colorful bands of red, yellow and brown in polished slices.
Structure: Wood replaced by silica
Full Petrified Wood 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 petrified wood and turritella agate?
Petrified Wood is a fossil with a Mohs hardness of about 6.5–7 and a waxy to vitreous luster, usually brown, red, yellow, gray or black. 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 petrified wood from turritella agate?
Petrified wood shows grain and growth rings, not spiral shells.
Could you tell them apart from a blurry close-up?
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