ShareRocks and Soils - What Do You See?
Imagine that you have just entered the store of your dreams. It is filled with all kinds of sweet, colorful candy. You immediately spot a very large display of lollipops. You have a quarter and you decide to buy one. You ask the cashier for a watermelon lollipop. She has just started working there that day, and is confused because there are no labels on the lollipops. She does not know which of the many different lollipops is watermelon.
You're The Scientist
Think about the above problem. On a sheet of paper describe
how you could solve the problem of determining which sucker is the watermelon
flavored lollipop?
Narrowing The Field!
Write down the steps you would use to determine which
one is watermelon. Now compare your steps to the steps taken below.
Perhaps the first thing you would do, is to look at the color of the lollipops. You might be able to eliminate some of the lollipops based on color. For example, black lollipops are probably licorice flavored. Yellow lollipops might be lemon flavored. Watermelon colors are usually a pink, red or green color. After looking at the lollipops, you decide it is probably one of four that you picked out based on the color. What could you do to find out which of the four lollipops is watermelon? Your next step might be to smell each of the lollipops. Red lollipops might also be cinnamon flavored, and cinnamon flavoring has a very distinct smell. By the process of elimination you have been able to narrow your lollipop search down to two lollipops. Are there other ways to identify which lollipop is the watermelon flavored candy? What would you do now to find out which lollipop is watermelon?
Common Sense!
You are probably wondering what the above story has to
do with rocks and minerals. In the story, you identified the watermelon
lollipop by using your senses. You first looked at the lollipop's appearance.
Next, you smelled the lollipops. Finally, you tasted the lollipops. You
can also identify minerals by their physical properties. You can learn
to identify many minerals by their appearance. Other properties used to
identify minerals include smell, feel, and how a mineral might sound when
it is tapped.
Hardness
One physical property of minerals is their hardness.
Some minerals such as talc are very soft and can be scratched with a fingernail.
You already know that diamond is very hard and nothing can scratch it.
Other minerals
fall somewhere in between. The scale on the right was invented by a scientist
named Frederich Moh. He made this scale to help people determine the hardness
of minerals. Every mineral has a specific hardness.
Streak
When
you rub a mineral against the back side of a porcelain tile it will leave
a streak. Sometimes the streak is the same color as the mineral. Sometimes
the streak is a different color. And sometimes there is no streak at all.
Different minerals have different streaks.
Test Time!
There are several other tests that can help to identify
minerals. Some minerals will fizz if you put vinegar, which is an acid,
on them. Sulfur can be identified by its rotten egg smell, and halite
(rock salt) oddly enough, tastes like salt (remember that you should NEVER
taste a rock without permission from an adult.) There are minerals that
glow under ultraviolet light. Minerals all have different weight. All
of these physical properties are useful in mineral identification.
Identify it!
Collect several rocks or have your teacher provide you
with some samples. Use a mineral classification key to identify the samples.
Be sure to record your test results to explain your identification methods.
Make it!
Make a mineral alphabet book. After observing the minerals,
organize your findings alphabetically by their names.
- On a sheet of paper, cut out or draw a picture of the mineral.
- Record the following information about the mineral:
- Name of mineral
- Composition (elements from which it is made)
- Physical properties (hardness, streak, etc.)
- Uses
- Other interesting facts about the mineral
- Repeat this process using as many different letters of the alphabet as you can. When you have completed the above steps, make a cover sheet and bind the papers together.
