Thin Sections

  • A highly colorful thin section is pictured

    Polarized light reveals a rock's mineral composition.

  • A metallic colored thin section is pictured

    Fossils and rock fragments are seen in this thin section.

At the Michigan Geological Repository for Research and Education at Western Michigan University, we have an extensive collection of thin sections.

Thin sections are very thin slivers of rock (about 30 μm thick) cut from cores. When examined with a polarizing microscope, these samples reveal the mineral composition and fabric of the rocks. That data is used to evaluate reservoir quality, environment of deposition and to compare these direct observations to porosity and permeability measurements obtained indirectly, such as by wireline logs. The MGRRE thin section collection documents over 2500 sections available for on-site viewing.