Manual of Minerals
Manual of Minerals
Looking down a petrographic microscope - physical or virtual - for the first time can be a bewildering experience. So much is unfamiliar that it can be difficult to know what you're looking at, or looking for. One way of fixing this problem is to obtain a relevant geoscience degree that includes instruction in optical mineralogy, how to drive a polarizing microscope, and all the mysteries of igneous, metamorphic and sedimentary petrology.
Alternatively, you may just want to dive in and explore. We've created the Manual of Minerals to help you do this. The Manual is not a comprehensive optical mineralogy course; it doesn't worry too much about the theory behind what you see down a microscope. Our aim is to provide bitesize morsels of practical advice to guide your observation, alongside clear examples of typical features, common minerals and interesting textures you may encounter in thin sections. We've also added a 'rogue's gallery' of oddities, anomalies and flaws that occur in many thin sections for various reasons and confuse novice and expert users alike at times! We hope that pointing out these pitfalls will save you time by keeping you focused on the geology.
This resource was initially created by Stelios Karastergios, University of Milano-Bicocca, with additions by Huw Sheppard, University of Oxford, during separate internships at the Open University in the Virtual Microscope suite. Further additions may be made sporadically if the VM elves snatch clandestine breaks from their routine duties.
There are four sections in the Manual - you can access each of them using buttons under the headings below, or via the links on the sidebar.
- FEATURES
Mineral properties
This section introduces some key properties of minerals that can be used to help identify and understand them in thin section. If you are unfamiliar with rocks under the petrographic microscope, this is a good place to start discovering how to observe and interpret what you see in the microscope images.
- MINERALS
Mineral examples
This section lists several common minerals with descriptions of properties that will help you identify them in thin section, along with links to typical examples in the Virtual Microscope. We aim to gradually expand this section by adding more minerals as time and resources allow.
This catalogue was initially created by Stelios Karastergios, University of Milano-Bicocca, with additions and refinements by Huw Sheppard, University of Oxford, during separate internships at the Open University in the Virtual Microscope suite.
- TEXTURES
Microscopic textures
This section describes some examples of common microtextures in rocks, aiming to aid recognition rather than offer in-depth discussions of the processes that form them. Some microtextures provide valuable insights into the origins or evolution of rocks and brief comments on these aspects may be included.
- TRICKSTERS
Oddities and anomalies
Many thin sections contain strange features that seem designed to trip up unwary petrographers and distract them from the geological wisdom they seek. These glitches in the images have a variety of causes: some muddle and confuse, while others appear weirdly beautiful or intriguing. All microscope users have been bamboozled at one time or another by one of these microscopic gremlins, so recognising them for what they are is a valuable skill!