EVSC 2800 Chapter Notes - Chapter 4: Olivine, Pyroxene, Pumice
12 May 2016
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Document Summary
Mineral grains- the most common type of grains in rocks. In situ mineral grains are present in the rock where they originally formed, they lock together to form the rock. Detrital mineral grains are not ingrown and do not lock together to form the rock. They were removed from the rock in which they originally formed and became part of another rock. Clasts- weathering causes big rocks, animal shells, and plants to be fragmented into broken pieces called clasts. Bioclasts are plant fragments and shells or bones that have been separated or broken: gravel, sand, silt, and clay are names for size classes of clasts. Glassy rocks have no visible grains and break along wavy, curved, glossy surfaces. Fine-grained rocks are made mostly of grains that are barely visible and too small to identify even when magnified with a hand lens.
