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).

Note that there are better less confusing depictions of the unit cells than the ones currently (2024) on wikipedia.

It seems titanium (Ti), tin (Sn), and lead (Pb) have stable oxides with the same structure. Last one most stable.
Opening up the possibility of checkerboard mixing series neo-polymorphs eventually making the structure more stable.
Just like in the case with stishovite and rutile there is the neo-polymorphic checkerboard mixing series of the mechadensites.
(wiki-TODO: fins a name for these neo-polymorphic mixing series)

Same structure with other elements - potential for neo-polymorphs

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 be enforcable via mechanosynthetic synthesis.

Related

• Stishovite – simlar density and high hardness (Mohs 8.5 to 9.5)
• Base materials with high potential
• Silicon
• Base materials with high potential

External links

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