Sapropel

Sapropel (stress on the last syllable: / Zapro ˑ pe ː l /) or digested sludge ( ancient Greek σαπρός sapros " lazy ", " rotten " ) is produced under natural conditions in nutrient- rich waters and marshes, when organic material in the absence of oxygen is converted biochemically. They form fine-grained masses, which are colored gray to deep black by H2S formed from metal sulfides. Digested sludges can solidify and form a rock, the Sapropelit that due to the relatively small proportion of organic material to the Akaustobiolithen, the non- combustible organogenic sedimentary rocks ( Bioliths ) counts.

Examples

An example is the well-preserved exceptionally by their wealth of fossils from the Eocene world famous Messel Pit near Darmstadt. The lack of dissolved oxygen in the water body and the lack of flow ensured that the bodies of dead animals during the embedding in the sediment rather than by the subversive activities of the bottom dwellers ( benthos ) were disturbed in their embedding position.

A poor mixing and limited exchange of soil water, such as may occur in largely isolated sedimentary basins, formed an oxygen-free and reducing ( euxinisches ) environment. Again, digested sludge, which is called after solidification to sedimentary rocks as Schwarztonstein or Schwarzpelit forms. Euxinische conditions still exist at the bottom of the Black Sea and in deeper areas of the Baltic Sea. For the dark color ensure finely divided carbon and iron sulphides, mainly pyrite. In addition, black shales may be of valuable metals, such as copper, uranium and vanadium enriched.

Examples of significant deposits of Schwarzpeliten are locally erzreiche copper shale of the Upper Permian of Central Europe ( Zechstein ), the Devonian black shales of the Central German Uplands (including the roof shale of the Eifel) and known for its unique fossils Posidonia shale from the German Lower Jurassic.

Sapropelkohle

If organic material is largely free of inorganic rock material, it will, under appropriate conditions to coal. Sapropel or digested sludge coal produced in the edge region of a humus coal, where the formation conditions are no longer optimal, and hence the coal rank is low. For this reason, the original ingredients are easy to recognize. If the Sapropelkohle from plant spores, it is as cannel, even Kannel or Kännelkohle (of English. Candle candle = ) denotes dominated the algal component, one speaks of Bogheadkohle. Is it very finely layered and can be split into thin sheets leathery consistency, we also speak of charcoal paper or Dysodil. Due to their content of volatile bituminous shares Sapropelkohle is highly flammable and is therefore counted as Kaustobiolithen, the combustible organic sedimentary rocks ( Bioliths ).

Sapropelkohle is quite soft and is suitable for carving figures, with traditional carvings mostly show mining motifs.