Silicified coral is a fossilized remain where original coral structures have been replaced by microcrystalline silica. Collectors often look for distinct patterns and pore structures retained from the original coral organism, which can be beautifully preserved through agatization.
Is this silicified 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 silicified coral with a known reference. Silicified 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. Silicified Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Silicified Coral typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, gray, brown, red, yellow, pink.
- 5Look at form & habitTypical habit: massive.
Often confused with
Silicified Coral vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside silicified coral
Minerals reported to co-occur with silicified 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
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Decorative, Collector
- Host rock
- Sedimentary Limestone
- Typical price
- $5-100 per specimen
Where rockhounds find silicified coral
11 mapped spotsClassic worldwide localities
- Florida, USA
- Tampa Bay, USA
- Indonesia
- Madagascar
Field-hunting tip
Look in sedimentary limestone country — that is the host setting where silicified coral typically forms. If you start seeing quartz, calcite, goethite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Florida, Iowa, New York — start trip planning there.
Common questions
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Find silicified coral on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
