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Projects and experiments with minerals
I have been asked for projects to do with minerals, so here are some ideas for teachers, or students looking for projects.
You can see minerals in use all around. Metal is used widely, and it isn't always iron or steel. You may find copper, in electric cable or in water pipes. Saucepans are often made of aluminium. Gold and silver is used in jewelry, and silver in cutlery. You could get together a collection of metal objects and think why each particular metal was chosen (iron is strong, but rusts; copper conducts heat and electricity well; gold is beautiful and never decays; aluminium is light and doesn't taint food). It's possible to buy metal ores in mineral shops, and this website lists ores of iron, copper and other metals. This often look completely different from the final metal, and you could introduce the idea of elements and compounds and simple chemistry. You could also investigate what properties metals have, or why they are different from other materials: their shininess, their stength, the ability to be shaped easily, or to form a sharp edge, their ability to be drawn out into a wire or beaten flat. You could investigate metals throughout history: the Bronze Age, the Iron Age, and the metals used in a computer, or the light and strong metals necessary to build aeroplanes.
Rocks are often used as building material. Even if you think all your local housing is brick or wood, try looking at churches or gravestones or castles, or even the floor of your local shopping mall. What stone is used? Is it limestone or sandstone or even marble? Do you have a local stone used for building, or has it come from elsewhere? Is it a good building stone, or does it wear badly? Don't forget the roofs. Do they use slate? If the buildings are made up bricks, then are they all the same colour? This might mean that they are made from local clay. You can compare buildings near you with buildings in a different part of the country.
Jewelry is always fascinating. Why are some stones valuable and not others? What are precious metals? It's no good just saying they cost more! Jewlery has been admired throughout history and appears in literature. Rich people have always worn jewelry, and you can see this in their portraits. It might be hard to find real jewels, but you will be able to find photographs and descriptions.
A very ancient use of minerals is pigments for wall painting or cosmetics. You can make pigment yourself. Please be very careful not to use poisonous minerals! Red hematite is good, if you can find it, since it is just an iron oxide (like rust!), it makes a good colour, and it has a very ancient history indeed. Under its other name, red ochre, I have found it in practically ever list of paint pigment from pre-historic cave painting to modern lip-stick! Use a very small chunk. See the pigments page for details.
Some properties of minerals are a little harder to find, so could make an experiment in themselves. You can find the weight of a mineral sample by weighing it, but of course a big stone will weigh more than a small stone. What you are interested in is its specific gravity. This is weight/volume. How do you find the volume of an irregular solid? A teacher could set this as a problem. I suggest a solution using water (rather like Archimedes and his bath!) Put a beaker in a basin, and fill the beaker with water. Put the stone in the beaker, which will, of course, overflow. This water in the basin will have the same volume as the stone, and it's easy to find the volume of some water! Most serious books on minerals give their specific gravity. Another, more scientific, method is to use a spring weighing device with a hook, such as is used for weighing fish (but you will need a more sensitive device which measures grams). Tie the stone to the hook, and weigh it. Now lower the stone (only) into water, and note the change in weight. The specific gravity is the weight in air divided by the change in weight. Pumice is so light that it floats, but unfortunately this isn't true of other stones, so it's not very useful as a way of sorting out heavy from light minerals! Perhaps the easiest way is to hold it in your hand, and see if it feels heavier or lighter than you expect.
Another important property is hardness of a mineral. If one mineral will scratch another, then it is harder. You could get some stones and try to order them. However, many stones in rock shops are silicates, which will have the same hardness, very hard! You want a different collection of stones. In fact, any tumbled stone will tend to be quite hard, so try to find some other softer stones. Steatite or soapstone (right) is a soft stone often used for cheap carvings and beads. You can see whether you can scratch the stone with your finger-nail, or with the point of a steel blade (not perhaps a suitable experiment for young children!)
Some minerals have wonderful optical properties. The feldspars are great fun, as is tiger's eye. Transparent calcite has double refraction, and Ulexite transmits light in an odd way. Kunzite is dichromatic, as is iolite. You might not be able to find these particular minerals, but you can look at more common optical properties. Minerals can give you wonderful examples of translucent, as well as transparent and opaque. A cornelian just glows with the light behind it.
You might want to try identifying minerals. It's hard to identify stones that you find in your garden, or on a beach. But if you can get buy some minerals, especially if they are identified, then you can build up a collection which you can work with. There are shops that sell minerals. They might be serious shops (they often sell fossils as well), or they might be New Age shops (don't depise these - they can be extremely knowledgeable about the stones they sell). Museums with a geological collection often sell minerals as well. If the minerals are identified, then make a note of what they are! It may seem obvious, but it's easy to forget. The cheapest stones are tumbled and are usually silicates such as amethyst, rose quartz, rock crystal, agates and jaspers. These are fun to get, as they are brightly coloured, but since they are all basically the same mineral, try to get some other minerals as well. See if you can find some natural crystals, not just quartz, but calcite and pyrite to compare. Also look at whether the stones are transluscent, transparent or opaque. In fact, you can buy any stone that you like the look of - it's probably an interesting mineral for one reason or another!
Once you have a collection of named minerals, then you can work out how people could identify them. Some minerals are obvious from colour alone, such as malachite with its stripes of green. But others can be mis-identified - both amethyst and fluorite can be purple, for example. You can tell calcite crystals from quartz crystals by their shape. Some minerals such as tiger's eye or labradorite have lovely optical effects. If you get two of each distinctive mineral, then you could go through half of them, explaining what they are, and the sort of things that the students could look out for, and then let them try to identify the rest of the stones. But watch out for students taking a liking for a stone and quietly stealing it!
A more complex project might be to build up a branching database of minerals. You ask a series of questions: what colour is it; is it shiny; is it transluscent; and so on. Then you place the minerals at the end of their correct answers. There are a lot of questuions that you can ask about minerals, which make them very suitable for this type of project. If you have the necessary computer software, then you can put the data on the computer. If not, then spread the stones out on paper on a table, with the questions (and answers) written on the paper. Or the floor if the tables are too small! You can make up the database yourself, or get the students to do it, or start it off, and get them to add more questions for further minerals.
I hope this will give you some ideas. Please e-mail me if you think of any other.