Experiments: Rocks and Minerals

Look at Rock Crystals

Materials you need are:
a magnifying glass
various types of rocks (e.g. granite, basalt, rock salt)

Use a magnifying glass to observe both the size and shape of crystals in rocks.

Fool's Gold

Materials you need are:
a gold ring
a piece of white paper or a white floor tile
a piece of fool's gold (iron pyrites or iron sulphide)
your teeth

Rub a gold ring on a piece of paper and it should not leave a mark. Now bite the gold and it should be soft enough to leave an impression.

Do the same with the fool's gold.

You should find that fool's gold (iron pyrites) is much harder than real gold, and leaves a black streak on the paper.