Understanding "Inorganic"

Like "naturally occurring", the word "inorganic" is part of the definition of a mineral. This word can be confusing. It reminds many people of organic food, but in the science of geology is has a very different meaning. In this case, inorganic means that the object is not alive, and was not a part of anything that was alive.

To explore this, we will use the same materials that we used to explore "naturally occurring." You will need as many of the items from the following list as you can find:

  • several mineral specimens
  • several rock specimens
  • coins, bone, teeth, sea shells, wood, nails, cloth, glass, feather, paper, water, salt, pepper, other objects made of different materials

Once again, we will sort the objects into piles, but this time we are sorting them into organic and inorganic objects. As you look at each object, ask yourself, "Was this ever alive? Was it part of a living thing?"

OK, so let's try a few from the photo above. We will start with an easy one. Look at the snail shell in the center of the photograph. Was it ever alive or part of a living thing? Yes, it was produced by a salt water snail. That tells us that it belongs in the organic group, and it is not a mineral.

Just below the snail shell are a couple of iron nails. Are they inorganic?

Were they ever alive? No. Were they part of a living thing? Again, the answer is no, so the nails belong in the inorganic group. That does not mean that they are minerals, but it does tell you that they fit this part of the definition.

Again, some of the objects may take some thought.

For example, what about the dollar bill?

Was it ever alive, or part of a living thing? Your first response may be no, but that dollar bill is made of cotton paper. Where does cotton come from? It is the fibers produced by a cotton plant, which is a living thing. So the dollar bill is made from materials that were once part of a living thing. It goes in the organic group, and is not a mineral.

Some of the objects may be even tricker.

In the bottom, right hand corner of the photograph, you will see a coiled fossil of an ancient creature called an ammonite.

Ammonites were living things, so your first instinct is probably to put this in the organic group. If you picked up the fossil, and examined it closely, you would find that all of the original material from the ammonite is gone. It has been replaced by chemicals from the surrounding rock. The materials in this fossil have never been alive, so it goes in the inorganic group, even though it looks like a living thing. The chemicals that replaced the ammonite might be minerals. They certainly fit this part of the definition.

If you will be doing this activity with younger students, use objects that are easier to sort. If you are working with more advanced students, be sure to give them some challenges that will really make them think.