As a kid, Dr. Claudia Mora wasn't particularly interested in science. "I thought I might become a poet," she says. She changed her mind after taking a geology class in college. "It was the most interesting thing I'd ever done. So I kept taking geology courses."
Dr. Mora is a geochemist. Geochemists use their knowledge of chemical processes in nature to study the way the Earth formed, how it has changed over time, and how it might change in the future.
Dr. Claudia Mora discusses geology with a group of girls.
Geologists study different parts of the Earth. Some study volcanoes or earthquakes. Others study the oceans. Still others consider how life on Earth evolved and has changed over time. Answering these questions requires a knowledge of biology, chemistry, mathematics, and physics, making geology a very broad subject--just like the Earth!
You may not be interested in geology (or any other type of science) right now. But Dr. Mora says, "Keep your options open! Get a good background in math and science. Then, if you change your mind, you'll be ready."
Most everyone has studied the Earth in some way. It can be as simple as picking up interesting rocks and wondering what kind they are. Here are some ways you can learn more about your collection of "whatzits."
First, take a magnifying glass and look at each rock you have collected. You will see a lot of different particles. The different particles that form a rock are called minerals.
Minerals are the basic components that make up the Earth's crust. There are hundreds of different types of minerals, but most rocks contain only a few types.
You can try some simple tests to find out what type of minerals your rock contains. First, how hard is it?
Geologists rate minerals on a scale of 1 (very soft) to 10 (very hard), depending on how hard they are to scratch. The softest mineral is talc, with hardness 1; the hardest is diamond, with hardness 10. You can use some common objects to scratch a rock.
For example, your fingernail is about hardness 2.5. If you can scratch a rock with your fingernail, then the rock must be less than hardness 2.5. A penny is about hardness 4, so if your penny makes a scratch on the rock, the rock must be less than hardness 4. (Likewise, if the rock can scratch the penny, the rock must be greater than hardness 4.)
Glass is about hardness 5; a knife blade is about hardness 5.5; and a steel fingernail file is about hardness 6.5. (Do not try scratching with these objects unless a parent or teacher is with you.)
Rocks of hardness 6 and 7 will scratch rocks of hardness 1, 2, 3, 4, and 5.
Next, try a streak test. Rub each of your rocks across a piece of unglazed porcelain, such as a bathroom tile. (You can buy single tiles at a home supply store.) You can sometimes determine mineral type by the color of the streak that is left behind. This is a more accurate test than simply looking at the rock's color, which may be affected by impurities.
Does your sample leave a red streak? It could contain hematite, an ingredient in rust. If it leaves a gray streak, it may contain sulfite. A green or brown streak indicates pyrite. Feldspar, gypsum, mica, and talc leave a white streak. So how can you tell one from another? Well, that's why geologists use more than one test!
You can also try breaking your rock and looking at the way it splits, or cleaves. For example:
Many minerals, however, break into very irregular surfaces. You may need to use another test to find out about them.
What if you try several tests and still can't figure out what type of rock you have found? "Don't give up!" Dr. Mora says. Sometimes local science museums have special days in which experts will identify people's unknown "finds," she says. So save your rock--someone else may be able to identify it.