Lab 09: earth: igneous rocks
Believe it or not, you are standing on igneous rock (unless you are standing on a coral head, which is illegal).
The Big island is one huge igneous rock, so pick up a piece and melt it with the sun.
MAKE SURE YOU USE THE DARTH VADER HELMET OR GREEN GLASSES
Your goal is to focus the sun's rays on a small spot using a large fresnel lens (like a normal lens in a camera, but made of grooves in a plastic sheet) and determine the melting point of igneous rocks on our island.
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Steps:
- find a darth vader welding helmet: some have fixed dark glass, others are "clear" until you see something bright like the sun.
- test your helmet by looking at the sun-if it is a cloudy day, you might be able to ignite wood, but you will need a clear full-sun day to melt igneous rocks to magma
- get the large plastic sheet that focuses sunlight-be careful handling it, and don't allow the focus to burn your feet or clothes
- start by holding the lens perpendicular to the sun-you will need two people working together to make this possible
- raise and lower the lens until you see a small bright dot on the ground
- put a piece of wood where you see the dot, and try to ignite it, measuring the temperature with the scanning thermometer
- repeat with burning the asphalt of the road (you will not be the first to do this), measure the temperature
- repeat with an aluminum can, measure the temperature
- If it is a full sun day, patiently aim at a piece of rock from around the elab-DO NOT use concrete or coral, concrete can explode if heated, coral is just nasty
- continue until you can see the rock bubbling (it will turn red first) and measure the temperature
- we have two types of cooled magma: a'a and pahoehoe-which did you create?
- what is the difference between each of these, and why?
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