The hardness of a mineral is determined by what it
will scratch and what scratches it. In 1822, the Austrian mineralogist Moh
devised a scale from
1 - 10 using 10 common minerals:
1 - Talc
|
6 - Orthoclase
|
2 - Gypsum
|
7 - Quartz
|
3 - Calcite
|
8 - Topaz
|
4 - Fluorite
|
9 - Corundum
|
5 - Apatite
|
10 - Diamond
|
We do not always have this set of minerals but the
following are usually readily available:
Finger Nail
|
2.5
|
Copper Coin
|
3.5
|
Pocket Knife
|
5.5
|
Scratches Glass
|
>6
|