Tistarite

• Pro: Titanium is common in earths crust (and in space)
• Pro: Hardness is high
• Pro: Crystal structure is simple
• Con? unit cell is a bit big

Overall a good large scale structural base material for gemstone metamaterial technology.

• Formula: TiO₂
• Hardness Mohs 8.5
• Crystal system: Trigonal (the same as sapphire but different unit cell)
• Density ~4.53g/ccm
• Refractive index: ?? – likely quite high

Misc trivia:
Titanium is in a unusual trivalent form here
(as in grossmanite a titanium chain silicate).

Related

• Titanium

Other polymorphs of same formula:

• Rutile
• Anatase
• Brookite

External links

• Wikipedia: Tistarite (quite limited info there as of 2021-06)
• mineralientalas.de: Tistarite (3D structure)