Happy Birthday, Frederick Mohs
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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.
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| 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.
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| Diamond – 10 |
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To see the Mohs Scale, click Number 3 on the left-hand side of the Geo Mysteries FAQs.
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Learn more about minerals.
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| 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!
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Speaking of growing your own crystals, you can make your own rock candy by growing sugar crystals. Check out the simple directions here.
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Explore gems and minerals at the Smithsonian website.
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| Azurite – 3.5 |
The Mineral Information Institute is a good resource for photographs of minerals.
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