January 29, 2011

Happy Birthday, Frederick Mohs

This German geologist (a scientist who studies rocks and minerals and the origin and structure of the earth) is most famous for his Scale of Hardness.

Talc - 1
Born on this day in 1773, Mohs compared the hardness of various minerals, comparing each to the others by scratching one mineral onto another. Obviously, a harder material can scratch a softer one, but a softer material cannot scratch a harder one. Using his comparative data, Mohs created a scale that goes from one of the softest minerals, talc, at Number 1 to the hardest mineral, diamond, at Number 10. Of course, some minerals fall between the numbers and can be expressed as a decimal. For example, tin is considered 1.5. Also, the hardness of non-minerals can be expressed using the Mohs Scale; fingernails are about 2.5, for example, and copper pennies are about 3.2.
Diamond - 10

To see the Mohs Scale, click Number 3 on the left-hand side of the Geo Mysteries FAQs

Learn more about minerals.

Amethyst - 7
Mineral Matters includes lots of information, some collection tips, and some quiz games.  Be sure to check out the section on growing your own crystals!

Speaking of growing your own crystals, you can make your own rock candy by growing sugar crystals. Check out the simple directions here

Explore gems and minerals at the Smithsonian website. 

Azurite - 3.5
The Mineral Information Institute is a good resource for photographs of minerals. 

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