Dryhead Agate is a highly sought-after variety of banded chalcedony found in the Bighorn Mountains of Montana. It is prized by collectors for its vibrant red, orange, and yellow concentric banding and fortification patterns typically found in small-to-medium sized nodules.
Is this dryhead agate?
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 dryhead agate with a known reference. Dryhead Agate sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Dryhead Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Dryhead Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: red, orange, yellow, white, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: nodular.
Often confused with
Dryhead Agate vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside dryhead agate
Minerals reported to co-occur with dryhead agate. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Nodular
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Deposits (Chugwater Formation)
- Typical price
- $10-100 per nodule depending on size and pattern
Where rockhounds find dryhead agate
Classic worldwide localities
- Bighorn County, Montana, USA
Field-hunting tip
Look in sedimentary deposits (chugwater formation) country — that is the host setting where dryhead agate typically forms. If you start seeing quartz, calcite in float, you are in the right ground. Field specimens usually show a nodular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find dryhead agate on the map
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