Rocks
Rocks are not all alike. They differ in colour, in how rough or smooth they feel, in how hard they are, and in the size of the tiny grains they are made of. A simple test of hardness is to scratch a rock with a coin: a soft rock gets a line, a hard one doesn't.
Depth 1 · Foundation
You can tell rocks apart by colour, roughness, hardness and grain size, and test hardness by scratching.
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- 1
Foundation
You can tell rocks apart by colour, roughness, hardness and grain size, and test hardness by scratching.
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