Clastic rock
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Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks, and smaller grains of rock broken off other rocks by physic
A thin section of a clast (sand grain), derived from a basalt scoria. Vesicles (air bubbles) can be seen throughout the clast. Plane-polarized light above, cross-polarized light below. Scale box is 0.25 mm.
Claystone from Montana
Conglomerate
Breccia. Notice the angular nature of the large clasts
Shale
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Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. Shale is characterized b
Shale
Sample of drill cuttings of shale while drilling an oil well in Louisiana, United States. Sand grain = 2 mm in diameter
Color chart for shale based on oxidation state and organic carbon content
Shale in Potokgraben, the Karawanks, Austria