Agatized coral is a fossilized coral where the original structure has been replaced by microcrystalline quartz through mineral-rich groundwater infiltration. Collectors look for well-defined, intricate coral polyp patterns preserved within a colorful, polished matrix.
Is this agatized coral?
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 coral with a known reference. Agatized Coral 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. Agatized Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Agatized Coral typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, gray, pink, brown, red, yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: botryoidal.
Often confused with
Agatized Coral vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside agatized coral
Minerals reported to co-occur with agatized coral. 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 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Botryoidal
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Jewelry
- Host rock
- Sedimentary Environments
- Typical price
- $10-100 per specimen
Where rockhounds find agatized coral
11 mapped spotsClassic worldwide localities
- Florida, USA
- Georgia, USA
- Indonesia
- Thailand
- Utah, USA
Field-hunting tip
Look in sedimentary environments country — that is the host setting where agatized coral typically forms. If you start seeing quartz, calcite, chalcedony in float, you are in the right ground. Field specimens usually show a botryoidal habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Florida, Tennessee, Georgia — start trip planning there.
Common questions
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Find agatized coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
