Quartz rock has a hardness of 7 on the Mohs scale.
The Mohs Hardness Scale is a standard scale used by geologists to measure the relative scratch resistance of minerals. Developed by German mineralogist Friedrich Mohs in 1812, it ranks minerals from 1 (softest, like talc) to 10 (hardest, like diamond) based on their ability to scratch one another.
Understanding Quartz Hardness (Mohs 7)
With a Mohs hardness of 7, quartz is quite durable and resistant to scratching. This means:
- It can scratch minerals with a lower hardness number (1 through 6).
- It cannot be scratched by minerals with a lower hardness number.
- It is hard enough to scratch common glass (which typically has a hardness of 5.5 to 6).
- Minerals with a hardness of 7 or higher (like topaz, corundum, and diamond) can scratch quartz.
This hardness makes quartz a popular material for various applications, including jewelry, countertops, and industrial uses, as it stands up well to everyday wear and tear.
Other Key Properties of Quartz
Beyond its notable hardness, quartz exhibits other distinct characteristics:
- Fracture: Unlike minerals that break along smooth, flat cleavage planes, quartz demonstrates any type of fracture when broken, never the flat surface of cleavage. This often results in conchoidal (shell-like) fractures.
- Streak: It does not leave a noticeable streak on white porcelain. The streak test involves rubbing a mineral across an unglazed porcelain plate; the color of the resulting powder is the mineral's streak. Quartz leaves no significant color.
- Luster: Quartz typically has a glassy luster, or shine. This refers to the way light reflects off its surface.
| Mineral | Mohs Hardness | Common Examples/Uses |
|---|---|---|
| Talc | 1 | Powder products |
| Gypsum | 2 | Drywall |
| Calcite | 3 | Limestone, Marble |
| Fluorite | 4 | Used in toothpaste (fluoride source) |
| Apatite | 5 | Source of phosphorus |
| Feldspar | 6 | Ceramics, glassmaking |
| Quartz | 7 | Jewelry, glass, countertops |
| Topaz | 8 | Gemstones |
| Corundum | 9 | Sapphires, Rubies, Abrasives |
| Diamond | 10 | Gemstones, Cutting tools |
Understanding quartz's hardness and other properties is essential for identifying the mineral and appreciating its suitability for various practical and decorative purposes.
