You can get a rock to tell you its name if you ask it the right questions like: How hard are you? Are you heavy or light? To find out about a rock's hardness, you use a Moh's scale which will help you to decide what kind of rock you have. This chart will explain the test:
|Talc||1||Easily scratched by fingernail|
|Gypsum||2||Scratched by fingernail|
|Calcite||3||Barely scratched by copper|
|Fluorite||4||Easily scratched by steel knife|
|Apatite||5||Scratched by steel knife|
|Orthoclase Feldspar||6||Scratches glass with difficulty|
|Quartz||7||Scratches glass and steel|
|Corundum||9||(no simple test)|
|Diamond||10||(no simple test)|
As you can see, rocks are compared to each other in terms of hardness to help determine what minerals are in them.
You can also use luster to narrow your search. Metallic minerals like silver shine in a bright light but non- metallic minerals, like talc, are dull looking in the light. That will give you another tip.
"Specific gravity" is another test that can be used. It is a way of determining the weight of a rock in relation to its size.
Color and texture are two of the easiest tests to do on rocks. All you have to do is look at them!
Streak is a test done by scraping the mineral against an unglazed white tile and checking the color that is left on the tile. Sometimes it will be different from the rock's color and that is another clue.
Cleavage is sort-of like a crash test for rocks because you break off a piece with a hammer and then see how it breaks. Some break off in chunks and layers or so on. Some don't have any cleavage at all and that is another important clue!
You can get a book at the library or look up some of our recommended web sites and you will get more information on what your results mean. We suggest you keep a notebook and take good notes.
Go back to the Mining Tunnels!