"...I guess the Mohs scale is similar to the Richter Scale,
where just one point can be the difference between a roll and a
catastrophe. Teresa "
Yes and no, Teresa. Yes, one point difference on either scale means
an order of magnitude much greater than one. However, there is a
logical mathematical order to the Richter scale, while there is no
mathematical order to the Mohs scale. The Richter scale is a
logarithmic order of magnitude scale of geological forces (volcanic
and tectonic). Each one point increment is exactly ten times greater
than the preceding whole number value and about thirty times greater
in the magnitude of energy.
Now, applying this type of scale to mineral hardness, what if we took
the minerals on the Mohs' scale and converted them to a logarithmic
scale using the values obtained from a Sclerometer. We could call
this something like the Mohs Modified Logarithmic Scale or Mohs MLS
for short. Well, lets try it:
Mohs Mineral Sclerometer Mohs MLS
10 - Diamond - 140,000 5.146
9 - Corundum - 1,000 3.000
8 - Topaz - 459 2.662
7 - Quartz - 245 2.389
6 - Feldspar - 191 2.281
5 - Apatite - 54 1.732
4 - Fluorite - 37 1.568
3 - Calcite - 15 1.176
2 - Gypsum - 12 1.079
1 - Talc - 1 1.000
As you see, Diamond becomes 5.146, while the softest, Talc, stays at
1. All but Diamond is squeezed into two whole units (1 thru 3).
Unless you can visualize a logarithmic scale in your minds eye, is a
logarithmic hardness scale much improvement at all? The difference
between Diamond and Corundum may seem small at first glance, 2.146
units. A logarithmic scale seems best left to orders of energy.
Anybody with a better idea for a hardness scale?