Identifing characteristics to classify local igneous rocks

Aim: To identify characteristics to classify igneous rocks.
Agenda:
Warm-up: what are 4 things that geologists need to do in order to correctly identify a rock?
Students will be introduced as employees of a construction company where they stumble upon an outcrop of curious looking rocks. Wanting to know more, they decide to collect the rocks to learn about how they got there, and whether they should continue with plans to build a building over the area.
1. Collect rocks in zip-lock bags. Photograph area rock collected; make any notes about environment in science journal.
2. The origins of the word “igneous” – Latin “ignis”=fire. Ignite charcoal, ignition in a car.
3. How are igneous rocks classified? Origins: Extrusive vs. intrusive. Texture: porphyritic. Mineral composition.
a. Rhyolite, Pegmatite, Porphyry – which of these rocks is intrusive, which is extrusive? Why? What is the difference between them?
b. Summarize igneous rocks in rock cycle using the 7 best word method.
4. Discover activity: Compare and contrast samples of granite and basalt. Sketch rock samples in journal.
5. With a partner, discuss where the rock was found and come up with a realistic history & timeline for the rock. How did it get to the surface? Why was it found where it was found? How did it form? What type of rock could it have been previously?
6. Research what is needed for sound construction in unstable environments.
7. Create slide show that will be presented to the building committee (class).