Horsetail fossils, particularly the genus Calamites, are the segmented, reed-like remains of giant prehistoric plants from the Carboniferous period. Collectors look for the distinct vertical ribbing and nodal joints preserved in sandstone or shale matrices, which clearly show the internal structure of these ancient vascular plants.
Is this horsetail fossil?
5-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 horsetail fossil with a known reference. Horsetail Fossil sits at Mohs 3-5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Horsetail Fossil leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Horsetail Fossil typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: gray, brown, black, tan.
- 5Look at form & habitTypical habit: segmented stems, ribbed internal molds, whorled leaves.
Often found alongside horsetail fossil
Minerals reported to co-occur with horsetail fossil. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-5
- Density
- 2.0-2.6 g/cm³
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal habit
- Segmented Stems, Ribbed Internal Molds, Whorled Leaves
- Cleavage
- None
- Rarity
- Common
- Uses
- Collector, Educational, Display
- Host rock
- Sedimentary Shale and Coal Measures
- Typical price
- $5-100 per specimen
Where rockhounds find horsetail fossil
Classic worldwide localities
- Pennsylvania
- West Virginia
- Ohio
- Nova Scotia
- Germany
- Czech Republic
Field-hunting tip
Look in sedimentary shale and coal measures country — that is the host setting where horsetail fossil typically forms. If you start seeing coal, sandstone, shale in float, you are in the right ground. Field specimens usually show a segmented stems, ribbed internal molds, whorled leaves habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find horsetail fossil on the map
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