Formula: Al2(PO4)(OH)3
Origin of name: From Greek auge = bright, for its pearly luster on the cleavage
Crystal system: Monoclinic
Crystal class: 2/m
Unit cell: a = 13.13 Å, b = 8.01 Å, c = 5.08 Å, b = 112.3°
Colour: Colourless, white, yellowish, pale aquamarine blue
Diaphaneity: Transparent
Luster: Vitreous, pearly on cleavage
Habit: Crystals thick tabular, prismatic to acicular, thin triangular plates; massive
Hardness: 4.5 to 5
Specific gravity: 2.70
Cleavage: 4; {110} perfect; {-201} good; {001} and {-101} imperfect
Streak: White
Synonyms/varieties:
Comments: Formed by hydrogen metamorphism of phosphate-bearing rocks in peraluminous sediments; in some high-temperature hydrothermal ore deposits.
| Back to Alphabetical list | Colour photos | Thin sections | SEM images | TEM images | vibrational spectra description | IR spectra | Raman spectra | N-IR spectra | F-IR spectra | IES spectra |