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Friedrich Mohs

Friedrich Mohs was a German scientist who studied minerals. He lived from 1773 to 1839.

He moved to Austria in 1801 where he found a job identifying minerals in a collection that belonged to a wealthy banker. He used physical characteristics of the crystals to decide what they were. One of the characteristics he used to identify minerals was hardness.

He knew that some of the minerals could scratch others and that if a mineral could make a scratch on another, it must be harder than the mineral that was scratched. He found that all minerals could scratch the mineral talc, so it must be very soft. He also found that diamonds were so hard that no other minerals could scratch them.

About a decade later, Friedrich created a scale from one to 10 to describe mineral hardness. He gave harder minerals larger numbers and softer minerals smaller numbers. Talc, the softest mineral, he assigned to one, the smallest number on the scale. Diamond, the hardest mineral, he assigned to 10, the largest number on the scale.

Was Friedrich making scratches on the Austrian banker's expensive minerals? The banker probably wouldn't have liked that! But geologists around the world do appreciate what Friedrich did. Geologists still rely on his scale today! We call it Mohs Hardness Scale.

Last modified May 6, 2003 by Lisa Gardiner.

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The Fall 2010 issue of The Earth Scientist, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!

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