Igneous Rocks Identification

Undergraduate introductory physical geology course for majors and nonmajors.

Some understanding of Plate Tectonics would help, but isn't required. Minerals ID lab needed first.

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.

Students explore the various textures and compositions of igneous rocks and then apply them to identify unknowns.

Classification of unknown igneous rocks.

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

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

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

Instructor's Key -- educator-only file

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Instructor's Key

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Student instructions:

LAB PART 1 -- PREREADING:

1. Find prereading in your lab manual and complete it in pencil.
2. Resources to assist:
   • IGNEOUS ROCKS ID: (20-min, 46 MB) Video only | Video w/CC and Study Quizzes | Script
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 any additional information that can't be "seen".

• Igneous Rocks BOX A Photo Album
• Igneous Rocks BOX B Photo Album
• Igneous Rocks BOX C -- Identification -- Photo Album.
  Apply what you learned above as well as other observable characteristics of the samples to identify each one. **NOTE: There are some repeats in this box: different versions of rocks that get the same name.
  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.

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

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.

Igneous Rocks Identification Activity Key -- educator-only file

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