hardness
of the mineral
| The
hardness of the mineral is measured for comparison with the
represented of the ten classes of the Mohs scale (Friedrich
Mohs, German mineralogist, Germode 29/1/1773 - Agordo 29/
9/ 11839). In her a material of a certain class is grazed
from those of the following classes and grazes all those of
the preceding classes. In the absolute scale of the hardness
(of Rosiwal), this is express in resistance to the
abrasion measured in proofs from laboratory and attributing
to the corindone the value 1000. Also for
the Knoop scale the values of hardness are absolute,
and they depend on the depth of the signs engraved on the
mineral one from a special utensil with point of diamond,
with which a force standard is practiced |
Mohs
Rosiwal and Knoop scale
| mineral
|
MOHS
|
ROSIWAL
|
KNOOP
|
| talc
or graphite
|
1
|
0.03
|
1
|
| gypsum
or sulfur |
2
|
1.25
|
32
|
| calcite
|
3
|
4.5
|
135
|
| fluorite
|
4
|
5
|
163
|
| apatite
|
5
|
6.5
|
430
|
| orthoclase
or feldespar
|
6
|
37
|
560
|
| quartz
|
7
|
120
|
820
|
| topaz
|
8
|
175
|
1340
|
| corundum
|
9
|
1000
|
1800
|
| diamond
|
10
|
140000
|
7000
|
  
|
