Breccia
“A mosaic of broken fragments”
Sedimentary
Breccia is a rock composed of angular, broken fragments cemented together in a finer matrix. Unlike conglomerate, whose fragments are rounded by water transport, breccia's sharp edges indicate the fragments weren't carried far from their source.
Composition
variable: fragments of any rock type, cement of calcite, silica, or iron oxides
Where Found
Meteor Crater (Arizona), Italian marble quarries, fault zones worldwide, volcanic regions
Mohs Hardness
Variable (depends on composition)
Fun Fact
Impact breccias found at the Chicxulub crater in Mexico contain evidence of the asteroid strike that likely caused the mass extinction of the dinosaurs.
Test Your Knowledge
What does the angular shape of fragments in a breccia reveal about its origin?
Related Specimens
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