This rock contains more quartz than either mudstone or shale. Siltstone is commonly laminated due to variations in grain size, organic content, or amounts of calcium carbonate.

TEXTURE This is a fine-grained sediment. The individual rock fragments and mineral grains in siltstone are too small to be visible to the naked eye.

ORIGIN Siltstone forms by the compaction of sediment of silt grade, which may have accumulated in a variety of environments, both marine and freshwater. The fossil content can be a guide to the precise environment of deposition. Because of the presence of feldspar, siltstone is said to be immature. A long-term weathering process would decompose feldspar.

Grain size: Fine

Classification: Detrital

Fossils: Invertebrates, Vertebrates, Plants

Grain shape: Angular