Seifertite

Seifertite is polymorph of SiO₂ with a very high density ( 4.294 g/ccm ) and probably hardness.
It's similar to stishovite in these aspects.

(TODO: find out if this polymorph is stable at ambient pressure (and room temperature). It certainly is sable as inclusion at room temperature.)

Seifertite might be almost as interesting as sthishovite as potenial base material for gemstone based metamaterials.
Only diminished by its slightly lower symmetry (orthorhombic instead of tetragonal).

Same structure with other elements

There is a lead (Pb) compound with the same structure as seifertit.
It's called scrutinyte (PbO₂).

Given silicon (Si) an lead (Pb) both form the same structure the elements between germanium (Ge) and tin (Sn) might very well too.
Even if they do not form naturally decently metastable neo-polymorphs may enforcable via mechanosynthetic synthesis.

Related

• Stishovite – simlar density and high hardness (Mohs 8.5 to 9.5)
• Silicon

External links

• Wikipedia seifertite
• Structure of the unit cell in 3D: [1]