Blue silicified coral is an ancient coral colony replaced by microcrystalline quartz through the process of silicification. It is highly prized by lapidary enthusiasts for its intricate, naturally preserved internal structures and its rare, calming blue hues often found in specimens from Florida.
Is this blue 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 blue silicified coral with a known reference. Blue 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. Blue Silicified Coral leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Blue Silicified Coral typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: blue, gray, white, tan.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Blue Silicified Coral vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside blue silicified coral
Minerals reported to co-occur with blue 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
- 2.58-2.65 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary Limestone
- Typical price
- $20-200 depending on quality and size
Where rockhounds find blue silicified coral
1 mapped spotsClassic worldwide localities
- Florida, USA
- Tampa Bay, USA
- Indonesia
- Georgia, USA
Field-hunting tip
Look in sedimentary limestone country — that is the host setting where blue silicified coral typically forms. If you start seeing calcite, quartz, dolomite 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 West Virginia — start trip planning there.
Common questions
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Find blue silicified coral on the map
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