Monomict breccia
A monomict breccia is made of broken fragments of a single rock type, crushed and reassembled.
A monomict breccia consists of fragments that all come from the same rock. It forms when an impact shatters a rock in place without mixing it with other types. The pieces are then compacted or cemented back together.
Many eucrites are monomict breccias: fragments of a single basalt, often with recognisable crystals broken into angular pieces. Some diogenites and ordinary chondrites are monomict too. Because all the fragments share one chemistry, a monomict breccia can be treated much like an unbrecciated rock for many analyses, though the impact may still have disturbed some radiometric clocks.
On a cut surface, a monomict breccia may look uniform at first glance, but close inspection reveals angular grains with fine crushed material between them. The term sits within a family: monomict, genomict and polymict breccias describe increasing degrees of mixing, giving a quick picture of how much a parent body's surface was churned.
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