Wavellite

A secondary mineral found most often in aluminous, low-grade metamorphic rocks. Usually found as radiating "starburst" clusters of green to yellow-green fibrous crystals on fracture surfaces in the matrix, these may grade into globular aggregates; more rarely in chalcedony-like or opaline masses, or stalactic; very rare as good distinct crystals. The OH analogue of fluorwavellite. Note: Allanpringite is a monoclinic-pseudoorthorhombic Fe3+-analogue of wavellite.

History

Activities related to discovery and approval of the group members

Structural context

Wavellite
Crystal System orthorhombicSpace Group Pnma
a9.603—9.6422 (9.6205)
b17.332—17.4146 (17.3652)
c6.975—7.0094 (6.9923)
alpha90
beta90
gamma90
volume1160.913—1176.98 (1168.1458)

Based on 4 measurements

Chemical context

Stoichiometric formulas

Wavellite
mindat.org
  • Feb. 10, 2025Al3(PO4)2(OH)3·5H2OMay contain some F replacing OH.
  • March 13, 2023Al3(PO4)2(OH,F)3·5H2O
IMA
  • March 13, 2023Al3(PO4)2(OH)3 · 5H2O
mineralogy.rocks
  • Aug. 30, 2022Al3(PO4)2(OH,F)3·5H2O

Elements recorded on EPMA

4
Al
4
H
4
O
4
P
3
F
1
Fe
1
V

Physical properties

ColorColor entities, recognized using a custom trained NER model
  • yellowish-green
    • greenish white
    • yellowish-brown
    • brownish-black
      • colourless
      • colourless
      Color noteOriginal color note from the source
      Green to yellowish-green and yellow, greenish white, yellowish-brown, brown, brownish-black, blue, white and colourless; colourless in transmitted light.
      StreakStreak entities, recognized using a custom trained NER model
        Streak noteOriginal streak note from the source
        White.
        Lustre
        Vitreous
        Greasy
        Pearly
        Fracture
        Irregular/Uneven
        Sub-Conchoidal
        Transparency
        Transparent
        Translucent
        Tenacity
        brittle
        Hardness
        3.5—4
        Calculated density
        2.37