Sedimentary Rocks

Sedimentary rock identification uses variable aspects of texture and/or mineral content. Textures include types like granular or clastic, bioclastic, and crystalline; grain sizes include gravel (coarse = large, visible), sand (medium = small, visible), silt (fine = invisible), and mud/"clay" (very fine = microscopic); and others like angular (sharp edges on surface) and rounded (smooth surfaces). Mineral contents include "evaporite" minerals like halite, gypsum, calcite, and silica; organic carbon (plant debris fragments); biogenic carbonates (calcite, aragonite, dolomite) and silica materials; and inorganic detrital quartz, feldspar, lithic (mixed silcate) fragments, and clays.