Wednesday, October 21, 2009

Question 1

Dear Friend,

I am happy to help you identify the "rock" you found. However, just because the object is hard does not mean that it is a rock. Minerals are the building blocks of rocks, and likewise rocks are composed of minerals. There is actually a good chance it could be a mineral! Minerals are homogeneous, naturally occurring, and generally inorganic solids. What this means to you is that if the solid you found appears to have a definite chemical composition and crystalline structure, it is most likely a mineral. If so, there are different ways to test out what kind of mineral it is. Some of these include tests for luster (shine), hardness, magnetism, reaction to HCl, and cleavage (how the mineral would theoretically break apart).
If this solid does not appear to be crystalline, then it is most likely a rock. Rocks are divided into three families: igneous, sedimentary, and metamorphic. There are visible differences between the three. Metamorphic rocks and igneous rocks look relatively similar, but metamorphic rocks have characteristic banding. Igneous rocks are classified by color, which can be felsic or mafic, and grain size. Sedimentary rocks often contain fossils and are formed by the banding of different rocks.
I understand that it might be difficult for you to tell the difference between a rock and a mineral. It is tough because at a first glance the two solids look the same. My advice to you is that the more you are exposed to rocks and minerals, the more you will understand the difference! Getting familiar with the crystalline texture of minerals will make it relatively obviously when a solid is not a rock. Good luck!

No comments:

Post a Comment