The Mohs Hardness Scale And Chart For Select Gems

Introduction

The Mohs Hardness Test is one of the most important tests for identifying mineral specimens. The Mohs Hardness Scale measures a mineral's resistance to being scraped by ten different reference minerals. Because most specimens of a given material are relatively near in hardness, the test is beneficial. Hardness is thus a valid diagnostic characteristic for the majority of minerals. In 1812, a German mineralogist named Friedrich Mohs devised the scale. He chose 10 minerals with varying degrees of hardness, ranging from talc (a very soft mineral) to calcite (a tough mineral) (diamond). 

Mohs  Hardness Scale And Chart For Select Gems

Mohs' hardness is a scale that compares the relative hardness and scratch-resistance of minerals. Other hardness gauges rely on the ability to indent the mineral being examined (such as the Rockwell, Vickers, and Brinell hardness - these are used mainly to determine hardness in metals and metal alloys). The scratch hardness of a material is determined by breaking chemical bonds, forming microfractures on the surface, or the displacement of atoms (in metals).

Minerals having covalent connections are often the hardest, whereas those with ionic, metallic, or van der Waals bonds are much softer. Therefore, it is important to establish which mineral was scraped while conducting mineral testing. Surface scratches may generally be felt by running the fingernail over the surface after the powder has been wiped or blown off. One can also obtain a sense of the variation in hardness between two minerals. Quartz, for example, will be able to scrape calcite considerably more efficiently than fluorite.

It's also necessary to apply enough force to scratch (if you don't use enough force, even diamonds won't scratch quartz. You must also ensure that you test the item you believe you are testing rather than a minor inclusion in the sample. This is where a tiny hand lens might come in handy for determining if the test region is homogeneous.

To assist you in determining the hardness of your favourite gemstone, we have compiled a list of Hardness Scale And Chart For Select Gems.

Why is hardness necessary?

High hardness has significant consequences in a variety of disciplines. Abrasives are used to shape and polish a variety of materials. Diamonds are used in cutting tools for the manufacture of metals and other materials and creating dies for wire drawing and cutting cores in oil wells and mineral prospecting. Emery, a corundum variant, is used in a range of abrasive goods that don't require diamond tools’ hardness (or cost).

Garnets were utilised in sandpaper as an abrasive. Talc is a very soft material that has been used in bath powders for a long time (talcum powder). Mineral exploitation is also crucial in sedimentary rocks. Harder minerals have a more remarkable ability to move longer distances along with river systems. Erosion, transportation, and lithification are all quartz processes ( change of sediments to rock).

Zircons are long-lasting minerals in the environment, and they may often inform geologists what sort of rock was used as the metamorphic or sedimentary rock. Many landscapes have mineral hardness visible in their topography. Quartz-bearing rocks are more resistant to weathering and create capstones, which protect buttes and mesa tops from erosion.

Conclusion

Almost entirely, the Mohs Hardness Test is used to assess the relative hardness of mineral specimens. When readily identifiable specimens are being studied or more complex tests are not available, this is done as part of a mineral identification method in the field, in a classroom, or in a laboratory. In manufacturing processes, hardness testing is used to ensure that hardening procedures such as annealing, tempering, work hardening, and case hardening have been completed correctly.