Rocks and Minerals

What is the difference between a rock and mineral. Rocks are composed of minerals. How do you tell the difference between the two? Rocks and minerals are made by the earth. Bricks, concrete and glass are man made and not considered a rock/mineral. I showed the children a crystal grown from a kit and they thought it was real but I explained it wasn't grown in the earth. I had a string of pearls and asked if they were minerals. NO, they grew inside of a oyster/clam. Minerals have never been alive. Rocks such as chalk, limestone, petrified wood were alive at one time. Minerals have the same crystal shape throughout them. Quartz always had a hexagonal crystal. Mica has a flat Crystal. Halite - cube. Rocks can have many crystals in them. Granite is a good example to see. It has quart, mica and feldspar normally.

We went through some tests to help identify minerals. First was using your tongue. I have a huge piece of halite that I licked and then bought a box of rock salt and gave everyone a piece to lick. I then explained that you shouldn't go around licking minerals. I should them a piece of lead and explained how some minerals were poisonous. Next test uses the nose, I passed around pieces of sulfur. I had the kids sniff it and they all said it smelled like smoke and I explained that they use it in matches. Sulphur burns with a purple flame, but if you light it do it outside or in good ventilation because it smells bad. The next test uses our fingernails as we do the scratch test. I gave each child a piece of talc and let them scratch it and make powder like baby powder. I then gave them a piece of quartz and had them try to scratch it, it's a 7 on the MOH's scale of hardness the talc is 1. Diamond is a 10 and could scratch quartz. The last test we did was using a magnet to check samples to identify iron.

There are 3 types of rocks, sedimentary, igneous, and metamorphic. I explained that sedimentary is layered like a sandwich. I had a piece of sandstone that they could see the layers throughout. Igneous is fire rock and is hardened magma or lava. We pretended that a candle was a rock that I melted and we said that the melting wax was the lava. When the wax hardened it became "igneous rock". Pumice and granite are good examples. Metamorphic is rock that has been changed by heat and pressure of having a mountain on it. I had a multicolored pack of modeling clay. I gave each student a small ball and told them that they were a mineral. A rainstorm came and washed the "minerals" into the lake, which was my palm. The water squeezed these together to form a sedimentary rock. I showed them what it looked like stuck together. If I melted our "rock" it would harden into an igneous rock. I told the students that they were mountains and was going to squeeze the sedimentary rock and make it metamorphic. We passed it around and squeezed and saw how it changed. I then showed them limestone and the marble that it would change too after millions of years of pressure.