The order of minerals from softest to hardest is defined by the Mohs Hardness Scale. It was developed by German mineralogist Friedrich Mohs in 1812. Here's the scale with a brief description of each mineral:

1. Talc: So soft you can scratch it with your fingernail. It's used in cosmetics and baby powder.

2. Gypsum: Can be scratched by a fingernail. Used in drywall and plaster.

3. Calcite: Can be scratched by a copper coin. It's the main component of limestone and marble.

4. Fluorite: Can be scratched by a steel knife. Used in optics and as a flux in metallurgy.

5. Apatite: Can be scratched by a steel knife. Found in bones and teeth.

6. Orthoclase: Can be scratched by a steel file. A common feldspar mineral.

7. Quartz: Can scratch glass. Used in making watches, computer chips, and many other things.

8. Topaz: Can scratch quartz. Used in jewelry.

9. Corundum: Can scratch topaz. Forms the gemstones ruby and sapphire.

10. Diamond: The hardest natural mineral. Used in cutting tools, jewelry, and other applications.

Key points to remember:

* The scale is relative, not absolute. A diamond is *much* harder than a piece of quartz, even though they are only one number apart on the scale.

* The scale is a scratch test. You determine a mineral's hardness by seeing what it can scratch and what can scratch it.