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.

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.

Lead (Pb) forms a stable mineral with this structure.
For titanium (Ti), tin (Sn) see papers in external link references.
This may open up the possibility of checkerboard mixing series neo-polymorphs eventually making the seifertite structure more stable but retaining hardness.
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)

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]

---

• Paper on titanium oxide in seifertite/scrutinyite structure. (better unit cell depiction than usually)
• Paper on tin oxide in seifertite/scrutinyite structure.