Quartz
From apm
Advantages:
- Silicon and oxygen are the two most common elements in earth's crust
- much lower than diamond but still decent hardness
Disadvantages:
- low crystal structure symmetry
- questionable passivatability
- much lower than diamond but still decent hardness
Related
Stishovite a polymorph of SiO2 other than quartz that is:
- much harder
- much denser
- has higher crsytal structure symmetry (the same as rutile)
- is metastable (hopefully)
There are several other known polymorphs of silicon dioxide.
One of them is Seifertite which is also a denser and harder thah quartz.
