The Mohs' hardness scale was developed in 1822 by Carl Friedrich Christian Mohs (a german geologist and mineralogist). This scale is a chart of relative hardness and resistance of the various minerals (1 - softest to 10 - hardest). Hardness is determined by scratching the mineral with a mineral or substance of known hardness.
Keep the following principles in mind when performing the hardness test:
"That which scratches is harder than that which has been scratched."
"Objects of equal hardness can be scratched with difficulty."
"Mohs scale does not indicate exact hardness, which depends upon the purity of the mineral sample and its degree of crystallinity."
andrei.apopei [at] uaic [dot] ro
Mg3Si4O10(OH)2
CaSO4·2H2O
CaCO3
CaF2
Ca5(PO4)3(OH−,Cl−,F−)
KAlSi3O8
SiO2
Al2SiO4(OH−,F−)2
Al2O3
C
