A fossilized fern is the preserved remains or impression of a prehistoric plant, found primarily in carbonaceous shale and siltstone. Collectors look for a high-contrast specimen where the organic carbon film has been preserved against a lighter or differently colored sedimentary matrix.
Is this fossilized fern?
4-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch fossilized fern with a known reference. Fossilized Fern sits at Mohs 3-6, softer than the next harder reference, harder than the previous one.
- 2Name the organismDecide what left the fossil before worrying about the rock. Organism: Ferns. Age: Fern crown group from about 423 million years ago (late Silurian).
- 3Read the lusterHold the specimen under a strong light. Luster: dull.
- 4Match the color rangeCompare against the expected color range: black, brown, gray, tan.
Often found alongside fossilized fern
Minerals reported to co-occur with fossilized fern. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-6
- Density
- 2.5-2.7 g/cm³
- Luster
- Dull
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Collector, Educational, Decorative
- Host rock
- shale, siltstone, coal
- Organism
- Ferns
- Age
- Fern crown group from about 423 million years ago (late Silurian)
Where rockhounds find fossilized fern
1 mapped spotsClassic worldwide localities
- Mazon Creek, USA
- Joggins, Canada
- Czech Republic
- Germany
- France
Field-hunting tip
Where it forms: shale, siltstone, coal. If you start seeing pyrite, siderite, kaolinite in float, you are in the right ground. In the U.S., the densest reported localities are in Oregon. Start trip planning there.
More fossilized fern photos
Common questions
How do you identify fossilized fern?+
Where is fossilized fern found?+
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What minerals are found with fossilized fern?+
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Find fossilized fern on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
