Vitrain is a lithotype of

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

formed from the

bark Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...

of large plants. Known for its glossy appearance, vitrain typically occurs in thin bands, between 3 and 10 millimeters in width. It has a brittle texture and typically forms cubical pieces when broken. Chemically, vitrain stands out among coal lithotypes by hosting large concentrations of

germanium Germanium is a chemical element; it has Symbol (chemistry), symbol Ge and atomic number 32. It is lustrous, hard-brittle, grayish-white and similar in appearance to silicon. It is a metalloid or a nonmetal in the carbon group that is chemically ...

. Combustion of vitrain proves a vital source of germanium production, where the element can be extracted from the leftover ash.

References

Coal {{mining-stub