Mohs Hardness Scale is named after its inventor, Friedrich Mohs. This means that an apostrophe is not needed when typing the name of the test. “Moh’s” and “Mohs’ ” are incorrect. Google is really smart about these names. You can even type “Moe’s Hardness Scale” as a query and Google knows to return results for…

The Mohs Hardness Test is almost exclusively used to determine the relative hardness of mineral specimens. This is done as part of a mineral identification procedure in the field, in a classroom, or in a laboratory when easily identified specimens are being examined or where more sophisticated tests are not available. In industry, other hardness…

When testing for hardness, remember that you are testing “the resistance to scratching.” During the test, some materials might fail in other ways. They could break, deform, or crumble instead of scratching. Hard materials often break when subjected to stress. This is a lack of toughness. Other materials might deform or crumble when subjected to stress.…

The hardness test developed by Friedrich Mohs was the first known test to assess resistance of a material to scratching. It is a very simple but inexact comparative test. Perhaps its simplicity has enabled it to become the most widely used hardness test. Since the Mohs Scale was developed in 1812, many different hardness tests…

Although reference books and websites often list a single hardness for each mineral, many minerals have variable hardness. They have greater or lesser hardness depending upon the direction in which they are being scratched. A well-known example of a mineral with variable hardness is kyanite. Kyanite frequently occurs in blade-shaped crystals. These crystals have a…

Diamond is not the hardest substance known, but the materials that are harder are much more rare. Researchers have reported that wurtzite boron nitride and lonsdaleite can be harder than diamond. It is unlikely that you will find a mineral that is softer than talc. However, a few metals are softer. These include: cesium, rubidium,…

An alternative to using the reference minerals for testing is a set of “hardness picks.” These picks have sharp metal points that you can use for very accurate testing. The picks allow much more control, and their sharp points can be used to test small mineral grains in a rock. The sharp picks can be…

Some people make their own hardness testing kit using a few common objects. The contents of their kit often include:  their fingernail a copper coin a nail a piece of glass a knife blade a steel file a streak plate a piece of quartz This field hardness testing kit sounds like a great idea. These items cost very little, and you can…