rocks
a human bone
They are almost as hard as rocks. The are considered a five hardness so that means about the same hardness as apatite. (a mineral)
Humans teeth are actually very soft to what all of thedentist say.
According to the Moh's scale of hardness, tooth enamel rates a 5; about the same as the mineral apatite, and less than feldspar or quartz. However, it's likely that the combination of materials in...
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