Quartz
The second most abundant mineral in the earth's crust and the reference point at Mohs 7, which is the practical dividing line for scratch resistance — anything softer than quartz gets scratched by ordinary dust, which is mostly quartz. It is piezoelectric, deforming when a voltage is applied and generating one when squeezed, and a quartz plate cut to the right orientation resonates at a temperature-stable frequency: that is the entire basis of quartz timekeeping. Its stiffness, conductivity and expansion are strongly direction-dependent in the crystal, so single figures for those are left off here.
Properties
- Density
- 2,650 kg/m³ — 2.65 g/cm³
- Melting point
- 1,670 °C
- Hardness
- 7 Mohs
- Floats in water
- No
- Magnetic
- No
What it is used for
- Watch and clock oscillators
- Optical windows and prisms
- Foundry sand and glassmaking
- Engineered stone worktops
How it compares
Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.
| Material | Density | Relative to water |
|---|---|---|
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| quartz ← | 2,650 kg/m³ | 2.65× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |
Does it rust?
Quartz contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.
Is it magnetic?
Quartz is not a metal and has no ferromagnetic response.
Common questions
- What is the density of quartz?
- 2,650 kg/m³, or 2.65 g/cm³.
- Does quartz float?
- No. At 2,650 kg/m³ it is denser than water.
- Is quartz magnetic?
- Quartz is not a metal and has no ferromagnetic response.
Related pages
Sources
- United States Geological Survey — USGS (Public domain (US Government))