Hardness
Some minerals are very hard, others are very soft. We can use the Mohs Hardness
Scale to compare the hardness of any mineral. The higher the number on the
scale, the harder the mineral is. Each mineral can scratch only those minerals
below it on the scale.
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| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
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| Gypsum | Calcite | Fluorite | Apatite | Orthoclase | Quartz | Topaz | Corundum | Diamond |
You can easily test hardness by trying to scratch a mineral with your fingernail and a pocket knife.
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| Your fingernail has a hardness of 2.5 on the Mohs scale. If you can scratch a mineral with your fingernail, it must be softer than 2.5. If you can't scratch it, it must be harder than 2.5. | A pocket knife has a hardness of 5.5 on the Mohs scale. If your knife can scratch a mineral, it must be softer than 5.5. If it can't, then it must be harder than 5.5. |
Now let's examine another mineral property:
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© The Children's Museum of Indianapolis, 2000