Anatase

• Titanium is common in earths crust (and in space)
• Hardness is decent
• Crystal structure is simple and unit cell is not overly big an complex

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

• Formula: TiO₂
• Hardness Mohs 5.5 to 6.0
• Crystal system: Tetragonal
• Density ~3.97g/ccm
• Refractive index: n_ω = 2.561, n_ε = 2.488 – quite high!

Related

• Titanium

Other polymorphs of same formula:

• Rutile
• Tistarite
• Brookite

External links

• Wikipedia: Anatase
• mineralientalas.de: Anatase (3D structure)