Akdalaite

Akdalaite (IMA symbol: Akd^[1]) is a very rare mineral found in Kazakhstan and has the formula 5Al₂O₃·H₂O.^[2] It was formerly believed to be 4Al₂O₃·H₂O. It is therefore the same as tohdite an artificially produced phase. Studies on the crystal structure and spectra indicate that this is an aluminium oxide hydroxide.^[3]

Akdalaite
General
Category	Minerals
Formula	5Al2O3·H2O
IMA symbol	Akd
Identification
Color	White, pale greenish yellow in thin section
Fracture	Irregular/uneven
Mohs scale hardness	7–7.5
Luster	Vitreous
Streak	White
Diaphaneity	Translucent
Specific gravity	3.68

White vitreous crystal aggregates of the extremely rare Al mineral akdalaite from the TL (Solnechnoye Mine, Kara-Oba, Karazhal, Ulytau Region, Kazakhstan) and only one of 6 known localities worldwide. Ex Vandenbroucke Museum collection from Waregem, Belgium.