Corundum vs Quartz
Corundum and Quartz are genuine alternatives to one another — a choice somebody actually makes — and differ on 3 measured properties, density most clearly.
Corundum vs Quartz
Corundum
Al2O3
Aluminium oxide — hardness 9, the mineral of ruby and sapphire, and a major industrial abrasive.
Quartz
SiO2
The second most abundant mineral in the Earth's continental crust, and the reference point for hardness 7 on the Mohs scale.
| Property | Corundum | Quartz |
|---|---|---|
| Crystal system Categorical values can be listed side by side but not ordered or subtracted. | trigonal | trigonal |
| Density | 3.95–4.1 g/cm³ higher | 2.65–2.66 g/cm³ |
| Lustre Categorical values can be listed side by side but not ordered or subtracted. | vitreous to adamantine | vitreous |
| Mohs hardness Mohs hardness is an ordinal scale: values can be ranked, but differences and ratios between them are not meaningful. | 9 higher | 7 |
| Streak Only one of the two has a figure we can stand behind, so there is nothing to compare. | Not known | white |
Choosing between them
Corundum is recorded as a substitute for Quartz — less toxic, stronger.
What it gives up: Costs more than sand, which is the only reason sand blasting persisted after the silicosis was understood.
Direct substitute, on the evidence cited above.