A silicified fern forms when ancient fern tissue is replaced molecule by molecule by silica-rich water over geological time, turning plant matter into stone. Look for intricate, detailed venation within the matrix, often preserved in shades of brown or grey from mineral impurities. It is popular in lapidary work for cabochons and display pieces thanks to its striking organic detail.
Is this silicified fern?
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 silicified fern with a known reference. Silicified Fern sits at Mohs 6.5-7, softer than the next harder reference, harder than the previous one.
- 2Name the organismDecide what left the fossil before worrying about the rock. Organism: Extinct tree ferns such as Psaronius and Tempskya. Age: Psaronius: Carboniferous to Permian; Tempskya: Cretaceous.
- 3Check the preservationPreservation: Silicified stems. That controls the weight, the hardness and how the piece takes a polish.
- 4Read the lusterHold the specimen under a strong light. Luster: vitreous to waxy.
- 5Match the color rangeCompare against the expected color range: brown, black, gray, tan, red, yellow.
Often confused with
Silicified Fern vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside silicified fern
Minerals reported to co-occur with silicified fern. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 6.5-7
- Density
- 2.5-2.7 g/cm³
- Luster
- Vitreous to waxy
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- sedimentary strata
- Organism
- Extinct tree ferns such as Psaronius and Tempskya
- Age
- Psaronius: Carboniferous to Permian; Tempskya: Cretaceous
- Preservation
- Silicified stems
Where rockhounds find silicified fern
1 mapped spotsClassic worldwide localities
- Arizona, USA
- Madagascar
- Germany
- Czech Republic
- Wyoming, USA
Field-hunting tip
Where it forms: sedimentary strata. If you start seeing quartz, chalcedony, pyrite in float, you are in the right ground. In the U.S., the densest reported localities are in Nebraska. Start trip planning there.
More silicified fern photos
Common questions
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Find silicified fern on the map
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