Cooking Rocks: Did the Experiment Work?

In-Class Activity 1_Rock Evolution and Change

Julia Kahmann-Robinson PhD and Marjorie Chan PhD, University of Utah Department of Geology & Geophysics

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Figure 1 Student experimental results in "Cooking Rocks"

Provenance: Julia Robinson, University of Utah
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

Purpose

Have students understand whether or not their experiment was successful based upon results and class discussion

Preparation

In this case students should do the homework before this activity. The students will need several days to do the homework at home. For this activity, make sure students have completed their "Cooking Rocks" homework.

Engage

Have students think about the fact that minerals can change under certain conditions. For example: graphite and diamond are c-based minerals.

• Presentation on diamond and graphite minerals: http://www.youtube.com/watch?v=qoC1tPGB61Q
• Movie showing conversion of synthetic diamonds to graphite: http://www.youtube.com/watch?v=7L7BV3IBfFA

For their homework experiment -

• Observe the following experimental results (left side examples are "before" and right side examples are "after"). Why are they different colors?
• Observe the experimental results in Figure 1. Was the experiment successful, why or why not?

Explore

1. Would you consider your experiment successful? Why or why not?

2. If any failures or issues presented themselves, why did they occur? How could you mitigate them?

Explain

1. As students discuss their experiment, particularly the results, explain what success in experimentation really means. Success isn't always equated to "the test worked". Sometimes there is much to be learned in what may appear as failure.

2. If students experienced "failure" help them to determine the parameters that can be changed, or ascertain from the students what they think prevented them from a successful experiment.

Elaborate

1. In your own words, define the term diagenesis:

2. How do goethite and hematite differ?

3. How did "cooking" the rock facilitate a change in mineral composition (be sure students recognize the difference between the inert host rock quartz grains vs. the diagenetic iron oxide cement)?

4. Explain how this diagenetic alteration could occur on Mars? Could the alteration occur today? Or in earlier Mars geologic history? Why or why not?

Evaluate

What do you think is the origin of the hematite in the TES image (figure 2) below? Consider the context of Meridiani Planum.

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Figure 2. Thermal Emission Spectrometer (TES) map of hematite abundance in Meridiani Planum, Mars. Image credit: NASA/JPL/Arizona State University

Provenance: NASA/JPL/Arizona State University
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

Image from: http://www.nasa.gov/mission_pages/mgs/20061121-imagesb.html

Note: on the relative abundance bar at the bottom, hematite abundances range from 5% (blue) to 20% (red). Hematite often forms in the presence of liquid water.