feinkörnige

Feinkörnige is a German term used to describe textures or structures in which the constituent grains are small. The form feinkörnige (and related forms like feinkörniges, feinkörniger) is commonly applied across disciplines such as geology, soil science, and materials science to characterize materials, rocks, soils, powders and related substances.

In geology and petrology, feinkörnige rocks have mineral grains that are too small to distinguish with the naked eye. These rocks often form by rapid cooling or rapid deposition, and include lithologies such as shale, mudstone, and some siltstones. Feinkörnige rocks are typically contrasted with grobkörnige rocks in which minerals are large enough to identify by sight, such as many granitic or plutonic rocks.

In soil science, feinkörnige refers to textures dominated by fine particles. Soils with high fractions of silt and clay are described as feinkörnig, as opposed to sandy soils. The grain-size distribution influences properties such as porosity, water retention, plasticity and erodibility. Classification systems use terms aligned with grain size to distinguish texture classes and guide agronomic management.

In materials science and metallurgy, feinkörnige microstructures indicate small, closely spaced grains within a material. Such fine grains can be produced by rapid cooling, alloying, or thermo-mechanical processing and often lead to increased strength and hardness via grain-boundary strengthening, sometimes at the expense of ductility.

Measurement of grain size typically involves microscopy or sieving, with standards that relate to specific size ranges. Feinkörnige is thus a relative descriptor, context dependent on the material and its application.