Coquina is a sedimentary rock composed almost entirely of poorly cemented shell fragments and mollusk debris. It is easily identified by its highly porous, conglomerate-like appearance and its distinct lack of a fine-grained matrix. It is commonly found in beach and shallow marine environments where high wave energy prevents the accumulation of silt.
Is this coquina?
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 coquina with a known reference. Coquina sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Transported shell fragments, poorly to moderately cemented, often bedded or cross-bedded.
- 3Pick out the mineralsComposition: Mainly calcite, often with some phosphate, as fragments of shells or coral. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: dull.
- 5Match the color rangeCompare against the expected color range: tan, white, light gray.
Often confused with
Coquina vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside coquina
Minerals reported to co-occur with coquina. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3
- Density
- 2.0-2.5 g/cm³
- Colors
- Luster
- Dull
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Construction, Decorative, Ornamental
- Host rock
- marine environments
- Texture
- Transported shell fragments, poorly to moderately cemented, often bedded or cross-bedded
- Composition
- Mainly calcite, often with some phosphate, as fragments of shells or coral
Where rockhounds find coquina
2 mapped spotsClassic worldwide localities
- Florida, USA
- Saint Augustine, USA
- Western Australia
- Brazil
- Spain
Field-hunting tip
Where it forms: marine environments. If you start seeing calcite, quartz, aragonite in float, you are in the right ground. In the U.S., the densest reported localities are in Florida. Start trip planning there.
Common questions
How do you identify coquina?+
Where is coquina found?+
Can I find coquina in the United States?+
What rocks look like coquina?+
What minerals are found with coquina?+
What kind of rock does coquina form in?+
What is coquina used for?+
Find coquina on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
