Altisite

Altisite is an exceedingly rare alkaline titanium aluminosilicate chloride mineral with formula [Na3 K6 Ti2 Al2 Si8 O26 Cl3], from alkaline pegmatites. It is a monoclinic-prismatic white mineral containing aluminum, chlorine, oxygen, potassium, silicon, sodium, and titanium.

It’s named after its composition (Aluminum, Titanium, and Silicon).

General information:

  • Formula: [Na3 K6 Ti2 Al2 Si8 O26 Cl3]
  • Color: Colorless
  • Lustre: Vitreous
  • Hardness: 6
  • Crystal System: Monoclinic.

Physical Properties of Altisite

The structure consists of (001) aluminosilicate tetrahedral slabs built up by the pentamer- where an aluminum tetrahedron shares its corners with four silicon tetrahedra. These slabs are connected by Ti octahedra and the resulting framework is crossed by three sets of infinite channels which contain the alkali atoms.

  • Lustre: Vitreous
  • Streak: White
  • Hardness: 6 on Mohs scale
  • Cleavage: None
  • Density: 2.64 – 2.67, Average = 2.65
  • Diaphaneity: Transparent
  • Fracture: Brittle – Conchoidal – Very brittle fracture producing small, conchoidal fragments.
  • Habit: Anhedral Grains – Granular minerals without the expression of crystal shapes
  • Luminescence: Non-fluorescent.

 

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