Virtual CollectionMain MenuThe Brock University Earth Sciences Virtual Collectionrocks, minerals, and fossils in a digital format.IndexHow to get to where you're goingERSC 3P90Index of samples for ERSC 3P90 LabsERSC 1P01 Mineral Sample image IndexDirections to the pictures of images for first-year Earth Science classesERSC1P01 Igneous Sample IndexIndex of igneous samples for first-year labsERSC1P01 Metamorphic Sample IndexIndex of metamorphic samples for first-year labsERSC 1P01 FossilsERSC Misc Rock Samples (unnamed)Whole rock sample imageryIgneous Rock samplesA place to explore rocks that have crystallized from molten materialVolcanic SamplesVolcanic samplesMeteoritesSedimentology Sample IndexAccess to sedimentology sample imageryMineralogy Quick Quiz PicturesA smattering of samples from the mineralogy collection to test your ability to recognize samples visually.A small collection of polished thin section viewsA small collection of polished thin section viewsRick Cheel4c2cab10f340dae1a53f5b584acd3f5528e40a41Mariek Schmidt3b678a5bd42eb8bf9a55fb761e5f17b11ce872c1Justin Pentescoe1b177acadc784b8497de179c36bc8e98f92c5e3Jordyn Schumacher063e6b5cd9d78fa0c5456d90b29abfa4f185e97cFrank Fuetendee05431475b87c68ebf15bbea4bfeac11808e9eAstride Silis79b69046c55b5f6cbc0bffd051aa83b3482e29a8
1media/13.jpg2022-07-27T15:50:42+00:00A small collection of polished thin section views12A small collection of polished thin section viewsimage_header2022-08-25T17:36:33+00:00Interested 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.
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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