What Is Mohs Scale: The Mohs scale is used to measured the hardness, the scale goes from 1, the weakest (talc), to 10 the hardest (diamond).

graph Mohs hardness

Who Created It: Friedrich Mohs, is the inventor of the Mohs scales, he created the scale on the years 1822. but who was Friedrich Mohs, he was born in 1773 in Germany, in the year 1801 Friedrich Mohs moved to Austria, and began working two different job. First, He was employed as a foreman at the Neudorf Mine in the eastern Harz Mountain region, but the job that brought the most interest to Mohs was his second job he was hired by a rich Austrian banker, J.F. van der Null, who had a large mineral collection which was in need of a curator. Mohs’ task was to sort the collection into categories, and to identify the materials that were still unknown. Mohs has to overcome a great challenge, because at the time, due to the fact that at the time there was nothing to measure the rock hardness. He found the theory, using the method use in botanic, where they categorize the plant by physical traits, therefore Mohs started to examine each mineral for common properties that would allow him to categorize them. Even if at the time was widely criticized by the mineralogical establishment. Since one of the most main trait all the mineral have together, was the hardness, also Mohs decide to concentrate on it.  Mohs noted that certain minerals could be used to scratch the surface of other minerals, so he reasoned that this scratch test could be used to rank minerals by their hardness. In this way he eventually ranked all the minerals according to their hardness. The scale ranged from the softest mineral which is talc, to the hardest, diamond.



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On the Mohs scale, diamond is rated 10, meaning that it can scratch all the other gems on the list; corundum (ruby and sapphire) (9), topaz (8), quartz (7), orthcoclase (6), apatite (5), fluorite (4), calcite (3), gypsum (2) and talc (1). To give an example of how the scale works, topaz can scratch all of the gems with a lower rating, but can be scratched by diamond and corundum.

Scale Specificity: The Mohs scale is only relative. It doesn’t tell us how much harder diamond is than corundum, topaz or quartz. Diamond is about 4 times harder than corundum, but corundum is only 2 times harder than topaz. Topaz, in turn, is twice as hard as quartz, but quartz is only about 25% harder than apatite.

Unique? : The Mohs Hardness scale is not the only test that has been invented, it is the 1st one ever created, and also the first one to be widely used worldwide. The Mohs hardness scale is still today the one which is the most used in the world to this test. Why is it the most used? The reason is simple, it is simple to used and is inexpensive, you could go out with just a pocket knife (hardness 5-6.5) and test it on random mineral to have a vague idea of it’s hardness. But you would know it’s Mohs Harness, if you use another test then you know it’s hardness on another scale.

Flaws?: It’s major flaws, is the fact that Mohs had only a limited mineral at the time, only time.

Mohs-Scale with rock

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