A fossil is the preserved remains, impression, or trace of ancient life found in sedimentary rock. It often undergoes mineralization, with the original material replaced by silica, calcite, or pyrite, producing a detailed replica of the original biological structure.
Is this 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 fossil with a known reference. Fossil sits at Mohs 3-7, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fossil leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fossil typically shows a dull to vitreous luster.
- 4Match the color rangeCompare against the expected color range: brown, gray, white, tan, black.
- 5Look at form & habitTypical habit: pseudomorphs after organic structures.
Often found alongside fossil
Minerals reported to co-occur with fossil. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-7
- Density
- 2.0-3.0 g/cm³
- Streak
- White
- Luster
- Dull to Vitreous
- Transparency
- Opaque
- Crystal habit
- Pseudomorphs After Organic Structures
- Cleavage
- None
- Fluorescence
- Variable
- Rarity
- Common
- Uses
- Collector, Educational, Decorative, Lapidary
- Host rock
- Sedimentary Strata
Where rockhounds find fossil
150 mapped spotsClassic worldwide localities
- Morocco
- USA (Wyoming)
- Germany
- China
- Madagascar
U.S. states with fossil
Each link opens a state-specific list of mapped rockhounding spots that produce fossil.
- Oregon25 spots
- Michigan13 spots
- Ohio12 spots
- Florida9 spots
- Maryland9 spots
- Nebraska8 spots
- Missouri7 spots
- New Jersey7 spots
Field-hunting tip
Look in sedimentary strata country, the host setting where fossil typically forms. If you start seeing calcite, quartz, pyrite in float, you are in the right ground. Field specimens usually show a pseudomorphs after organic structures habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Oregon, Michigan, Ohio. Start trip planning there.
Common questions
How do you identify fossil?+
Where is fossil found?+
Can I find fossil in the United States?+
What minerals are found with fossil?+
What kind of rock does fossil form in?+
What is fossil used for?+
Find fossil on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
