Hardness is measured on the Moh's hardness scale. Each of the values is a naturally occuring mineral. Testing devices (e.g. pencils) mount these in the tip.
10 Diamond
9 Corundum
8 Topaz
7 Quartz
6 Feldspar
5 Apatite
4 Fluorspar
3 Calcite
2 Gypsum
1 Talc
Ceramic glazes are the obvious candidate for this type of testing. If a specimen to be tested can be scratched by a mineral from the list, it is softer than that mineral. If it in turn will scratch another known mineral, it is harder than that mineral.
Tests | Hardness (Moh) |
---|---|
Tests | Glaze Hardness |
URLs |
http://www.gordonengland.co.uk/hardness/mohs.htm
Background Information on Mohs Hardness |