Welcome to Geosec Slides

A resource for geologists, amateur and professional, 
to aid the study and identification of rocks minerals and fossils.

Geosec Slides specialise in the production and supply of thin section microscope slides used as one of the two main methods of rock classification (the other being chemical analysis). Viewing thin section slides enables the geologist to identify the constituent minerals and textures of the rock. This, with information gathered from the site of collection, provides evidence of its chemical composition and the manner of its creation.


The slides reveal fascinating and beautiful internal structures, opening a window to parts of our world normally invisible. View through a microscope a hidden universe of colours and shapes, spectacular and intriguing, even without specialist knowledge.

It is a slip of rock, mounted on a glass microscope slide, and ground very thin. 30 Microns is the ideal thickness. (A standard piece of paper is 100 microns thick) At this thickness virtually all rocks are transparent, and the individual minerals that make up the rock can be seen and identified. When viewed through a polarising filter interference colours can be seen, a similar effect to oil on water. This too is used as an aid to identification.

Study of thin sections is a part of nearly all higher level geology couses, and experience in mineral identification is gained by viewing as wide a range of thin sections as possible. Geosec offers a large selection of slides from localities worldwide.

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