Dünnschliff

Dünnschliff is the German term for a rock thin section, a prepared specimen used in petrography and mineralogy to study rocks under a light microscope. The final product is a very thin slice of rock, about 30 micrometers thick, mounted on a glass slide and transparent to transmitted light. This allows observation of mineral grains, textures, and optical properties under plane-polarized and cross-polarized light.

The etymology derives from Dünn meaning thin and Schliff meaning grinding or grinding/polishing, reflecting the finishing steps of the preparation. In practice, the preparation of a Dünnschliff involves several stages: selecting a representative portion of the rock, cutting a suitable piece with a rock saw, and embedding it in epoxy resin to stabilize irregular shapes. The embedded sample is then ground and lap-seated with progressively finer abrasives, typically silicon carbide and then diamond pastes, to remove scratches and to approach a uniform thickness. After thorough polishing, the specimen is measured and mounted on a glass slide, sometimes with an additional resin layer, to create a stable, uniform thin section suitable for microscopic analysis.

Applications of the Dünnschliff include identification of minerals, assessment of rock textures and microstructures, and interpretation of geological histories, such as metamorphic or magmatic processes. It is a standard technique in geology, mineralogy, and related fields, enabling detailed petrographic description and quantitative or qualitative analysis of mineral modes and optical properties.

See also: thin section, petrography, polarized light microscopy, mineral identification.