Friday, 20 May 2016

Pebbles that make a good road

Friedrich Mohs, a German mineralogist, developed the Mohs scale of hardness in 1812. He selected ten minerals of distinctly different hardness that ranged from a very soft mineral (talc) to a very hard mineral (diamond). With the exception of diamond, the minerals are all relatively common and easy or inexpensive to obtain. 

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