The Hardness of a Mineral & Moh’s Number

The Hardness of a Mineral
One of the most essential and simplest ways of putting a mineral in a general class is by finding out approximately how hard the mineral is in the first place. This can be defined by what type of materials it can scratch and what materials are able to scratch it. The hardness of the minerals can be rated by Moh’s scale. This scale was developed by a German mineralogist in 1822 whose name was Friedrich Moh. Moh came up with a crude but practical technique of comparing hardness or scratch resistance of minerals. However it is not a mathematical progression of relative hardness but only consists of assigning numerical progression to ten different minerals arranged that have diverse degrees of hardness. This scale goes as follows:

Moh’s Number

1. Talc (the softest)

2. Gypsum

3. Calcite

4. Fluorite

5. Apatite

6. Feldspar

7. Quartz

8. Topaz

9. Corundum

10, Diamond (the hardest)

Scale kits can be found in different rock shops and you will be able to test the harness by using them. There are people that are doing studies on geology and that have the option of purchasing the diverse types of minerals as well. Obviously if you buy a gem it can cost you a bundle, but the price will be drastically reduced by buying synthetic gems and small amounts of what you are interested in trying out. Diamond can be acquired in the shape of a little rough diamond that is mounted in a metal bar that is then used to dress grinding wheels. If you ever find yourself out in the field without a hardness kit a lot of common items will give you an approximate estimate of the hardness of most minerals. For example, a toe nail can be equal to 2 and ½, a copper penny is around 3, and glass is around 5, knife around 6, a steel file around 7. Evidently this is only a reference and is refereeing to estimates. To be able to check for hardness many individuals start with softer tests. If it is noticeable that it is a soft mineral, a prospector or geologist will try to scratch it with his fingernails. If the by doing this the individual sees that this procedure does not cause a scratch on it, he will usually go for a pocket knife or a piece of quartz. If the quartz causes there to be a scratch, the next is a topaz test. If after doing the topaz test it does not scratch the mineral that is being tested but the quartz does, it means the mineral has a hardness of seven and eight. Usually you will not need to test more after this. If the mineral tests shows they are eight or above then it will be worthwhile to take it carry out an assay since most likely it is valuable or at least has some value in it. Unfortunately though, to be able to show that a mineral is between seven and eight in hardness is not much proof of anything, and a great deal of the minerals you will find will end up in this rage of harness as well. On the other hand, after you have found the harness of a mineral you will be able to do several other tests that will help to identify what you have found in the field.