Breccia is a clastic sedimentary rock composed of broken angular fragments of minerals or rock cemented together by a fine-grained matrix. Unlike conglomerate, the particles in breccia are sharp and angular, indicating they have not traveled far from their source before lithification.
Is this breccia?
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 breccia with a known reference. Breccia sits at Mohs 3-7, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Texture: Angular fragments bound by a finer matrix or cement. Grain size: At least 30 percent gravel-sized fragments (over 2 mm).
- 3Pick out the mineralsComposition: Coarse angular rock fragments. 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: gray, brown, red, white, variegated.
Often confused with
Breccia vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside breccia
Minerals reported to co-occur with breccia. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 3-7
- Density
- 2.0-2.8 g/cm³
- Luster
- Dull
- Transparency
- Opaque
- Rarity
- Common
- Uses
- Decorative, Architectural, Collector
- Host rock
- sedimentary basins, fault zones, volcanic pipes
- Texture
- Angular fragments bound by a finer matrix or cement
- Grain size
- At least 30 percent gravel-sized fragments (over 2 mm)
- Composition
- Coarse angular rock fragments
Where rockhounds find breccia
1 mapped spotsClassic worldwide localities
- Worldwide
- Italy
- Greece
- USA
Field-hunting tip
Where it forms: sedimentary basins, fault zones, volcanic pipes. If you start seeing calcite, quartz, limonite in float, you are in the right ground. In the U.S., the densest reported localities are in Oregon. Start trip planning there.
Common questions
How do you identify breccia?+
Where is breccia found?+
Can I find breccia in the United States?+
What rocks look like breccia?+
What minerals are found with breccia?+
What kind of rock does breccia form in?+
What is breccia used for?+
Find breccia on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
