Bean-shaped formations

BEAN-SHAPED FORMATIONS (EN: bean ore; DE: Bohnerze; FR: fers pisolitiques; ES: hierros ooliticos; RU: бобовины) are the natural mineral formations (concretions), with the ellipsoidal or spherical shape, with the size from 1 millimetre to 3 centimetres. They differ from the oolites by the absence of the concentric-shelly structure, they are homogeneous within the fracture. They emerge prevalently within the sedimentary rocks, sometimes forming the whole strata. There are widely known the clusters with the bean-shaped formations of the oxides of iron, aluminium, manganese (the so called bean ores). The bean-shaped formations with the sizes from the few hundredth parts of millimetre to 1-2 millimetres constitute the class of the microconcretions, and have the following morphological varieties: ooids (ovoids), globules, spherulites, oolites, while the bean-shaped formations, which are larger than 3 centimetres, which are having the concentric structure, are named as the pisolites.