Virtual Collection

A small collection of polished thin section views

Interested in chemistry, biology, and physics, but looking for a way to combine them all? Through Earth Sciences you can become a Geologist or Environmental Geoscientist who applies those subjects with a thorough study of planetary history, planetary processes, and materials to our natural world. One of the great things about the geological and environmental fields is that they allow you to combine your knowledge of seemingly disparate scientific disciplines to further our (humans that is) understanding of our own planet and our neighbouring planets. Some people in geology/environmental science work in labs, some in the field, and many in a combination of both.

You can learn more about options to study here: Brock Department of Earth Sciences


About our polished thin section display:

When a geologist needs to study a rock to determine its provenance (history and source) one of the first things they will likely do is have several polished thin sections (PTS) produced. A polished thin section is a portion of the rock mounted on glass and ground down to a thickness of 30 micrometers (about half the thickness of a strand of hair), it is then expertly polished.

A polished thin section permits light to be transmitted through non-metallic minerals (i.e., most minerals). Because rocks are made up of minerals, and minerals have a definite (and known) atomic structure forming a crystal lattice, the mineral can most often be identified by its optical properties (how light behaves as it passes, refracting or diffracting at planes in the atomic structure). Having done that, the rock's provenance can be distinguished when the texture of the microscopic view is considered with optically-determined mineralogy and the macro-scale environment. 

The study of rocks and minerals in this way is called optical petrology or optical mineralogy. The microscopes used to do this work are specialized, having a polarizing filter below the stage and another above the stage. Minerals' optical properties are also diagnostic when viewed with cross-polarized light (or crossed nichols). Metallic minerals are studied using reflected light and in many tell-tale crystallization characteristics still exist although most are a little more difficult to decipher. All of these properties are derived from the atomic arrangement of the mineral. Beyond optical petrology, geologists also routinely employ X-ray diffraction (both powdered-bulk and in-situ micro-targeted methods), electron microscopy, Raman spectroscopy, and X-ray Fluorescence.

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