Metamorphic Rock Identification

Katryn Wiese, City College of San Francisco

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Summary

Metamorphic Rock Identification online (developed for remote learning during COVID-19 pandemic); students will explore the various characteristics of metamorphic rocks and then apply them to identify unknowns.

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Context

Audience

Undergraduate introductory physical geology course for majors and nonmajors.

Skills and concepts that students must have mastered

Some understanding of Plate Tectonics would help, but isn't required. Minerals Identification Lab should have already been completed.

How the activity is situated in the course

One of a series of minerals and rocks labs that comes in the middle of the class AFTER covering plate tectonics, mountain building, structural geology, and maps.

Goals

Content/concepts goals for this activity

Students explore the various characteristics of metamorphic rocks and then apply them to identify unknowns.

Higher order thinking skills goals for this activity

Classification of metamorphic rocks

Other skills goals for this activity

By the end of this lab, students should be able to:

  • Observe and describe textures and composition of a provided metamorphic rock sample
  • Identify and name metamorphic rocks by hand sample
  • Compare and contrast textures and minerals within metamorphic rocks and what they indicate about the formation environment of the rock

Description and Teaching Materials

Student handout(copy of the relevant pages from lab manual)

Student instructions:

LAB PART 1 -- PREREADING:

  1. Find prereading in your lab manual and complete it in pencil.
  2. Resources to assist:
  3. By the assignment deadline, upload completed prereading IN CANVAS.
    **Note: you can submit your prereading early in pieces with a request for feedback -- an excellent way to learn the material and build on that learning.
  4. Review instructor feedback and answer key; make corrections; and seek help if needed.

LAB -- PART 2 -- MAIN SECTION:

  1. Find lab in your lab manual and complete it in pencil.
    **For online students, click on link below for at-home samples.
  2. By the assignment deadline, upload completed lab IN CANVAS.
    **Note: you can submit your lab early in pieces with a request for feedback -- an excellent way to learn the material and build on that learning.
  3. Review instructor feedback and answer key; make corrections; and seek help if needed.

REVIEW, REFLECTION, AND ASSESSMENT:

  1. Try to complete original lab again on own without looking up tables or resources.
  2. For rock quiz, you will need to be able to ID the rocks and describe particular characteristics (just like lab), but you will be limited in your time. The intention is that you will have learned all these rocks already and be able to ID them by sight BEFORE you start the quiz and without any aids. So be sure you practice them all enough before you start.
  3. Complete lab quiz in CANVAS.

ONLINE MATERIALS:

**For online students, complete the lab using your lab in the lab manual, as though you were IN class and holding samples. In lieu of face-to-face samples, click on the various links below to access photo and video footage. Note: there is no way to replace a hand sample with a video/image. You will not be able to feel textures, assess density, or manipulate the samples as you would like. However, there are some things you get better through online images and videos. Do your best!

**Samples in photo albums are in order in photo album, but to check on sample number, click on photo and then information icon: i. See same location for information on whether sample reacts to acid or not and any additional information that can't be "seen".

  • Metamorphic Rocks BOX A Photo Album
  • Metamorphic Rocks BOX B Identification Photo Album
    Apply what you learned above as well as other observable characteristics of the samples to identify each one.
    • **There are some repeats in this box: different versions of rocks that get the same name.
    • *One of the photos shows two polymorphs: kyanite (you're familiar with) and andalusite (haven't seen this one yet). You will see each of these minerals in at least one of the samples each. There might also be additional minerals you haven't seen before. You don't need to recognize things you haven't seen before, but you should be aware they might be there.
    • REMINDER: You will have to be able to identify these samples quickly and easily on the quizzes, so really be sure you understand what makes each sample unique.

Teaching Notes and Tips

See tips section and extra resources (all kept up to date for current students) on class website.

Assessment

I have students check answers against a key once they've turned in the lab. They are expected to make corrections and then study and practice before taking and end-of-week 20-minute quiz.

Here's how I handle the keys -- I release them to students AFTER the assignment deadlines -- so students can fully grade and review their own assignments. I grade the assignment they turned in for completion, thoroughness, and thoughtfulness, but not necessarily correctness. Turns out that if students aren't getting it, I can tell very easily by their answers, and I don't give them credit for answers that don't make sense, that don't fully address the question, etc. But if it's wrong, but they have a logical thoughtful effort applied, then okay. Students COULD technically get keys from previous semesters, other classes, or past semesters and use them, but if their answers are identical to any other students or to my key, they don't get credit. So in the end it doesn't help them. And most of their points come from weekly quizzes I have where I make them apply their understanding to new examples. The stakes are low on lab assignments because the answers don't need to be correct, just thoughtful and complete. I want to encourage students to use them to learn. Then I check that understanding on quizzes.

To get access to Lab Key, click on link to Google Document and request access, but be sure to include necessary evidence that you are an instructor teaching the course..

References and Resources

See tips section and extra resources (all kept up to date for current students) on class website.

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