Abstract

To overcome major challenges of teaching mineralogy and petrology classes that are based on hands-on instruction with a polarizing microscope, a collaborative effort resulted in a web-based resource of digitized thin sections and hand samples, called the "Virtual Petrography Laboratory". This tool enables instructors to select samples from a growing database and deliver them to their students as a digital laboratory set. Items include full thin section slides in plane and cross-polarized light, special 'rotatable' points under different magnifications and light settings, 3-dimensional hand sample models, and traditional photographs. Each customized selection can be easily embedded in learning systems, or distributed to students as a simple URL. Additional sample data is available to instructors upon request. Though we used this system as a pandemic-era substitute for in-person training, we note that it will also be useful as a supplementary resource with unlimited capacity for existing microscopy-based courses and as a highly accessible tool for those with difficulties using or accessing traditional microscopes. In this activity, we will train instructors with the basic functionality of selecting and delivering sample sets to their students. We will also provide examples of how we integrate the interactive content into a coherent laboratory exercise.

Context

This online educational resource is currently used in mineralogy and petrology classes at University of Toronto, Scarborough where second and third-year students are learning to use a polarizing light microscope for thin section analysis. We use the tool to create sample sets which we then supply to students who must go through a graded exercise to describe, identify, and interpret the sample. In this way, it simulates the normal procedure in traditional in-person lab exercises. We also use samples as exemplars during instruction to demonstrate certain features or properties of different minerals so students can become familiar with the procedures.

Why It Works

The Virtual Petrography Laboratory is effective as it allows students and instructors a flexibility that is not possible with the traditional brick and mortar laboratory. This online resource is not subject to the availability of expensive microscopes, restricted laboratory space, class size, instructional personnel, or location. Students can explore the entire database of hundreds of samples at their leisure if they wish to gain extra experience. It requires no installation, is cross-browser compatible, and highly accessible. Instructors can tailor-make their lab sets to complement their instructional plan. Those sets can be embedded in most learning management systems, or simply distributed as a URL. Basic sample data is publicly available on the website with additional detailed guides available to instructors. Virtual hand samples and thin sections are paired together so both can be accessed interactively. The 'rotatable' view points use a 360-degree rotation where students are in full control of the light source and magnification level in order to simulate how a real optical microscope works. This better prepares students for hands-on experience, and also increases their understanding of how light can be used to identify minerals.

Students of the 2020-2021 term Petrology and Mineralogy classes (University of Toronto-Scarborough) noted that the use of the provided Virtual Petrography tool was intuitive and easy. Furthermore, they remarked that the Virtual Petrography-based laboratories were an efficient substitution for the physical petrology lab exercises, that they were able to identify the minerals and rocks based on the provided media and that they were able to advance their skills on how to conduct analysis of thin sections based on optical characteristics of minerals. Instructors remarked that the use of the website and connected data table for thin section and media selection was intuitive and easy to maneuver.

1-Minute Introductory Video to the selection of a custom data set on the Virtual Petrography website: