Particle Composition

The mineralogical composition of suspended particles reflects their origin: mineral particles like quartz, feldspars, calcite, and clay minerals come from terrestrial erosion, organic compounds, calcium carbonate, and opal from organic production, phytoliths (formed in grasses) from semi-deserts, fly-ash from industry, rare micrometeorites from space. Although there are mineralogical analyses of suspended particles available, they are few and the most comprehensive data are for bottom sediments. Those for fine-grained deposits can be taken to reflect the composition of the material in suspension in the water column, but it should be realized that during or shortly after deposition part of the suspended material may have been removed by oxidation (organic matter) or dissolution (carbonate, opal), and clays may have been altered.