An agatized fern bud is a fossilized botanical structure in which organic material has been replaced by microcrystalline quartz. It usually appears as a distinct rounded or whorled nodular growth, found within sedimentary deposits or volcanic ash beds.
Is this agatized fern bud?
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 agatized fern bud with a known reference. Agatized Fern Bud 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 fern (genus Tempskya). Age: Cretaceous.
- 3Check the preservationPreservation: Agatized. That controls the weight, the hardness and how the piece takes a polish.
- 4Read the lusterHold the specimen under a strong light. Luster: waxy.
- 5Match the color rangeCompare against the expected color range: brown, tan, gray, white, black, red.
Often confused with
Agatized Fern Bud vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside agatized fern bud
Minerals reported to co-occur with agatized fern bud. 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
- 2.6-2.7 g/cm³
- Luster
- Waxy
- Transparency
- Translucent
- Rarity
- Uncommon
- Uses
- Collector, Lapidary, Decorative
- Host rock
- sedimentary strata
- Organism
- Extinct tree fern (genus Tempskya)
- Age
- Cretaceous
- Preservation
- Agatized
Where rockhounds find agatized fern bud
1 mapped spotsClassic worldwide localities
- USA (Utah)
- USA (Colorado)
- USA (Wyoming)
Field-hunting tip
Where it forms: sedimentary strata. If you start seeing quartz, calcite, barite in float, you are in the right ground. In the U.S., the densest reported localities are in Texas. Start trip planning there.




