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Friedrich Mohs

Every mineral collector should know about the Mohs’ Scale of Hardness and the mineralogist who developed it.

The scale is a list of minerals arranged from softest (No. 1) to hardest (No. 10) which is used to determine the hardness of all other minerals. 

Mohs’ Scale of Hardness:

  • 1. Talc
  • 2. Gypsum
  • 3. Calcite
  • 4. Fluorite
  • 5. Apatite
  • 6. Orthoclase Feldspar
  • 7. Quartz
  • 8. Topaz
  • 9. Corundum
  • 10. Diamond

Friedrich MohsThe mineralogist who created this scale was named Friedrich Mohs.

Friedrich Mohs was born on January 29, 1773 in the German town of Gernrode. His parents were merchants. He was well-educated. His early studies were in physics, chemistry and mathematics. Later on he took advanced studies at the mining academy in Freiberg, Germany. One of his professors at the academy was Abraham Werner who is another important figure in mineralogy. Dr. Werner inspired Friedrich Mohs’ interest in minerals.

In 1801 Mr. Mohs moved to the country of Austria. One of his jobs there was as the
curator of a private mineral collection that was owned by a banker named J.F. van der
Null.

 

    a “curator” is a person who takes care of a collection of some kind.

Mr. van der Null wanted his collection to be organized into categories. He also wanted Mohs to identify the many unknown minerals in his collection.

Believe it or not, in the early 1800’s no one had created a system for identifying minerals. So, Mr. Mohs started to study the different physical properties of minerals as a way to identify them. He noticed that some minerals are very soft, others are extremely hard. He also observed that harder minerals could scratch softer ones. With this in mind, Friedrich Mohs decided to develop a scratch test where he could determine the hardness of a mineral.  To make his scratch test more accurate and helpful, he carefully observed many minerals and created a list of 10 minerals that he arranged from softest to hardest.

To this very day we know this list as “Mohs’ Scale of Hardness.” 

 

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