A diamond is exceptionally hard, registering 10 on the Mohs scale of mineral hardness. This makes it the hardest known natural mineral.
The Mohs Scale of Mineral Hardness
The Mohs scale, developed in 1812 by German geologist and mineralogist Friedrich Mohs, measures the relative scratch resistance of various minerals. It is a qualitative ordinal scale, meaning it ranks minerals from softest to hardest based on their ability to scratch one another. While it's not a linear scale (the difference in hardness between 9 and 10 is much greater than between 1 and 2), it provides a useful and widely accepted standard for mineral identification and property assessment.
Here's a look at the Mohs scale:
| Mineral | Mohs Hardness | Characteristics |
|---|---|---|
| Talc | 1 | Very soft, easily scratched by a fingernail. |
| Gypsum | 2 | Can be scratched by a fingernail. |
| Calcite | 3 | Can be scratched by a copper coin. |
| Fluorite | 4 | Can be scratched by a knife. |
| Apatite | 5 | Can be scratched by a knife or glass. |
| Feldspar (Orthoclase) | 6 | Scratches glass; can be scratched by a steel file. |
| Quartz | 7 | Scratches steel and most common minerals; principal component of sand. |
| Topaz | 8 | Very hard, used in abrasives. |
| Corundum | 9 | Extremely hard (e.g., rubies and sapphires); used in industrial abrasives. |
| Diamond | 10 | The hardest known natural material; can scratch all other minerals. |
For more detailed information on the Mohs scale, you can explore resources like geology.com.
What Does a Mohs Hardness of 10 Mean?
A rating of 10 signifies that a diamond is the hardest mineral, capable of scratching every other mineral on the Mohs scale, including corundum (which is a 9). Conversely, nothing can scratch a diamond except another diamond. This characteristic is fundamental to its value and utility.
Why is Diamond So Hard?
The exceptional hardness of diamond stems from its unique atomic structure. Diamonds are composed entirely of carbon atoms arranged in a highly compact, strong, and rigid tetrahedral lattice. Each carbon atom is covalently bonded to four other carbon atoms, forming an incredibly stable and impenetrable network. These strong chemical bonds require a tremendous amount of energy to break, making diamond resistant to scratching and abrasion.
Practical Applications of Diamond's Hardness
The extreme hardness of diamonds makes them invaluable beyond their aesthetic appeal in jewelry. Their superior abrasive qualities are leveraged across various industries:
- Cutting, Grinding, and Drilling Tools: Diamond-tipped tools are essential for cutting, grinding, and drilling through very hard materials like concrete, stone, ceramics, and other metals.
- Abrasives and Polishing Agents: Diamond dust and powder are used as abrasives for polishing other diamonds and precious gems, as well as for industrial polishing applications where high precision and surface finish are required.
- Industrial Applications: Diamonds are used in specialized applications such as high-pressure research, precision machining, and as components in high-performance electronics due to their thermal conductivity and durability.
The unparalleled hardness of diamond ensures its significant role in both luxury and industrial sectors worldwide.
