Hard and soft rocks

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Q1: How can you tell which is a hard rock and which is a soft rock?

[Answer]

There are many kinds of rock. Some are hard, others are soft.

All rocks are made from tiny bits and most of them are held together with natural 'glues'. It is the type of glue that can make a rock hard or soft.

If you rub soft rocks together you may be able to rub some grains away. Then you can see how big the grains are.