Information for Teachers


Igneous and Metamorphic Rocks is an online resource for learning igneous and metamorphic petrology. In many ways it is like printed petrology textbooks in that it introduces the fundamental concepts of petrology to students who are taking their first course with a focus on igneous and metamorphic rocks. However, it is different in concept from a paper textbook in that readers are provided with study tools to engage actively as they read and explore information about igneous and metamorphic rocks. For example, readers are given control over phase diagrams with buttons, sliders, and mouseover effects. They can select data or upload their own data to be plotted on a variety of geochemical diagrams. There is an extensive visual Rock Library to use as examples or reference. And interactive questions are provided to provide feedback on concept understanding.

Ways to Use this Website

This website was imagined as a resource to help you teach and to help your students learn about igneous and metamorphic petrology. It is not intended as a petrology encylopedia, but focuses on petrology topics common to first petrology courses. Throughout, the emphasis is on interactivity, rather than on exhaustive topic coverage. It was created with the goal of providing online tools that will use the power of the reader's browser to animate diagrams used by petrologists, enabling the reader to explore what is shown, and hopefully to understand some of the petrology behind the diagrams. For this to work, you the teacher should ask your students questions and give them assignments that can be answered and completed by using the interactive tools provided.

Previously, you might have asked your students to answer similar questions without these tools. But many students are daunted by ternary graphs and phase diagrams, or struggle to plot various geochemical diagrams and models. The interactive tools provided here give the student immediate feedback and help them see how the diagrams work and respond to changes. As a result, students spend less time trying to figure out the mechanics of the diagrams and models and, therefore, are able to spend more time learning the larger petrologic concepts revealed by the diagrams and models.

Because much of what is unique about this website is found in the interactive figures, the figures are collected in lists by topic. Links to all those lists are given here: Collected Figure Lists. Browse the figures, being sure to try the mouseover, slider, click and other selections to see the options and possibilities. Think about what you could ask your students to do — questions they could answer — by using the diagrams. For many diagrams that plot or use geochemical data, notice that you can provide your students with data (or ask them to find data on PetDB or elsewhere) that they can upload to the diagram in a .csv format file (geochemical data file format instructions). Example of short activities or questions (with answers) based on interactive figures can be found around the website as part of the text. Larger study projects can be found on the Igneous Activites or Metamorphic Activies lists. More activites are in process, and if you have a project that might be useful to others and that you are willing to share, please contact me ( about incorporating it into this website with credit to you.

Additional Reading

My principal goal in creating this website is to use the power of browsers and the internet help undergraduate students learn petrology. Therefore, my focus has been to create interactive diagrams and other learning tools, not to attempt to match the more thorough coverage of igneous and metamorphic petrology in the many outstanding printed petrology textbooks. For those who wish to use this website as their course textbook, I recommend using additional readings from Elements (links provided) and other sources that suit the particular class. Student membership in MSA ($20/year) provides access to all Elements and American Mineralogist papers.

Static Figures for Your Use

The strength of this website is in the interactive figures. Use these figures in your classes. Give your students assignments that use them. However, if you want static versions of the figures to use in a presentation or or assignments, this is how to download the images or files.

Screen Capture. Regular screen capture can be used on any webpage. The pixel resolution of the captured image will depend on the pixel dimension of the image on the screen from which the image is captured.

Download Full-sized JPG or PNG Files. Images, such as those of rocks or thin sections that are pixel based, may have a pixel dimension that is greater than can be displayed on your screen. To download the original image at its full pixel dimension, do the following:
  • Click on the “Load HiResImage” button if there is one.
  • For Chrome, right click on the image and select “Inspect”; mouse over the highlighted image source filename (usually a .jpg file); double click the popup image to open the image only in a new Chrome Tab; right click on the image there and select “Save Image As.”
  • For Safari, right click on the image and select “Inspect Element”; click on the highlighted image source code with a filename (usually a .jpg file); right click on the highlighted filename and select “Save File.”
  • For FireFox, right click on the image and select “Save Image As.”

Download SVG Files. Many of the graphs and drawings are vector-based (zoomable) .svg files. For these images, you can directly download the .svg file (same instructions for Chrome, Safari, and FireFox). Right click on the image and choose “Save Image As.” The filename of the image with .svg will appear in the popup window. For most .svg files, you can also download the original file by right clicking on the thumbnail image in a list of figures. SVG files can be placed directly into Microsoft programs such as PowerPoint and Word. They can be opened in and edited to suit your needs by vector graphics software like Adobe Illustrator, Affinity Designer, CorelDraw, Inkscape, etc.

Print as PDF. Some images have pixel graphics and vector graphics, such as the lever rule info that appears on those phase diagrams with a “Show Phase %” button. Other images have .svg elements that are added dynamically, such as the variation diagrams. For these images, there is no one file to download. However, if you print one of these pages as a .pdf file, that file can be opened in and edited to suit your needs by vector graphics software.

You Can Help Make this Website Better

Contribute Photos. The rock library and rock naming sections will be more useful with more rock photos. In particular, please send me good photos of outcrops, rock samples, and thin sections in ppl and xpl, as well as permission to use them. I will add the photos to the library along with the metadata you send and give you credit for the images. The more information you provide about the rocks in the images, the more useful the images will be to students using the website. If the images are of rocks studied in a paper, please send the reference. If you have location information (latitude and longitude), that makes the images more valuable. If you have a mode, if you have an age, if you have a story about the rock, I will include those data in the library entry. Be sure to include scales in or approximate scale information with your photos. Send the images in the highest pixel resolution you have.

Submit Activities. The website will be more useful if it contains more student-active learning modules. If you have a problem set or assignment that works with diagrams or data that you are willing to share, I would like to consider making it available on this website and give you credit for it. I do not promise to take all offers of material, but I hope there will be many activities for teachers and students to choose from. I am particularly interested in activities that have good learning goals and that encourage students to make use of the tools provided on the website. If the data used in the student activity are taken from a published paper available for follow-up reading, the activity will be especially useful. If a new or modified interactive diagram or computational tool is needed, I will consider making it. Share your good activity ideas and many will benefit.

Suggest Web Links. The advantage of a website is that it can use or link to interesting and useful information, images, and videos on other websites. Please send me links to information online that you find useful and think would be helpful in learning petrology. I will add the links where appropriate, incorporating images as links or directly if permission can be obtained. I would also like more interesting earth science links that could be used in the Procrastinate list (click the Procrastinate-pause button, lower right on the footer bar for a random link to a website on the list).

Why Study Petrology? In the Introductory Topics section, the first topic is "Why Study Petrology." I would like to add many more reasons to the randomly accessed list of questions and answers (Motivation) . If you have an image and question, or perhaps a video or video link and a question, that you think would be good, please send them to me. Also, I hope to add short (30 seconds?) videos of petrologists answering this question (see Expert Opinions). If you like this website, consider sending me a short video of you with one or more of your personal favorite reasons for studying petrology.

Report Errors. This website is under construction! More content is added regularly. I am writing the code as well as assembling the content. Please note and tell me ( about typographical errors, broken links, and errors of fact or interpretation. I will try to fix them as I learn about them. I also welcome ideas about ways to improve or expand the website.

Thanks in advance for your help!
--John Brady (