Rock Identificaation

Directions

•This is a group exercise. Each group will have 3 students. Check the Announcements section of the course to find out who you are going to work with.

•Each person should find two (2) different rocks (not minerals). These can be rocks that you were given, rocks that you bought, or rocks that you found (on the street, in the woods, please do not chip them off any public structures… there are plenty of free rocks to be had).

•Write a short paragraph describing each of the two rocks (thus two paragraphs).

•Photograph each rock with a sense of scale (a pen, a coin, a ruler). The photographs must be in focus. Use the “macro” setting on your camera; usually it’s indicated by a little “tulip” icon like this:

•Post your pictures in the Rock Identification Working Area discussion board (one thread per assigned group of three students).

•With your assigned group (again; see Announcements), collectively identify your rocks and verify each other’s identifications. You can seek validation of your identifications from the instructor.

•Once the identifications are solid, collaborate to answer the following five questions for each rock sample in the group:

1.What type of rock is this? (igneous, metamorphic, or sedimentary)

2.What are the dominant minerals in the rock? (e.g., quartz, biotite, calcite, etc

3.What is the name of the rock? (e.g., basalt, granite, sandstone, etc.)

4.Where is this rock from? (Where did you obtain the rock?)

5.What processes were responsible for creating this rock? (Interpret the history behind this rock sample.)

If igneous, describe the character of the melt that generated the rock (mafic or felsic) and its cooling history (aphanitic vs. phanertic: extrusive or intrusive?).&?ßsp;

If sedimentary, describe the depositional environment in which the rock originally formed (not the environment/location where you found it!).

If metamorphic, describe what the rock was prior to metamorphism and speculate on what forces may have caused it to metamorphose (burial, continental collision, meteor impact, igneous intrusion, etc.).

•Go to the Rock Identification and Interpretation Gallery discussion board, and post your finalized (1) photos, accompanied by your (2) identifications, and (3) interpretations. Each group should have six total rocks on display in the Gallery.