How to do Mohs hardness test?

What is Mohs Test?

The scientists or researchers need to perform various tests to discover the secrets hiding in the nature.

Often, they come in touch of unknown elements like rocks, minerals, etc. which are needed to identify. Measuring the hardness of these solid materials is also a way to identify them.

The Mohs hardness test is the popular way to determine the hardness.

Normally, the geologists use this method and perform the test to get a rough idea in the field about the objects.

A hardness scale is there which helps to do the test and ten different types of minerals are used as reference minerals. The reference minerals are, talc (H=1), gypsum (H=2), calcite (H=3), fluorite (H=4), apatite (H=5), orthoclase (H=6), quartz (H=7), topaz (H=8), corundum (H=9) and diamond (H=10). Among them, only diamond is the rare and expensive mineral. All others are quite easy to find.

Talc is the softest one while diamond is hardest in the list.

The hardness of all these common minerals is already discovered and well known.

How to do the test?

At first, you need a clean area or surface to do the test. Now, take the unknown object which is needed to test.

Hold the element and scratch it with any of the reference mineral. Press the unknown element with the reference one and examine whether there is any scratch on the sample or not. If the sample mineral has any scratch, then that specimen has equal hardness or less than the reference one.

READ  How to test quartz hardness and luster?

So, you can compare the hardness of that unknown object with the help of this known mineral. You can repeat the test with a different reference mineral to be surer.

Sometimes it is not possible to carry all the reference tools.

Even fingernails (H=2.5), knife with a steel blade (H=5.5) or a penny (H=3) can be used to find out the result. If you know the hardness, then it is easy to know whether the unknown material is harder or softer than these mentioned ones.

For an example, if you can scratch the surface of the object with fingernail, but not with the penny, then it is harder than gypsum but softer than calcite.

Fingernails’ hardness is 2.5. Gypsum is only 2 while a penny is just as hard as calcite. So in this way you can determine the hardness and compare it with the reference table.

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