Wöhlerite Group

A group formally established by IMA in September 2020 (Proposal 20-D). It has its name after the first described mineral of the group, wöhlerite (Scheerer, 1843). It includes 12 minerals (as of September 2024) with both monoclinic and triclinc structures. They occurs as accessory phases in various geological environments as nepheline syenites, alkali feldspar granite and skarns and calc-silicate marbles from different localities worldwide. Formerly also known as 'Cuspidine Group.' See also the related Rosenbuschite Group.

History

Activities related to discovery and approval of the group members

Structural context

Monoclinic System
22 measurement(s) or 59.46%9 member(s) or 81.82%
Triclinic System
9 measurement(s) or 24.32%2 member(s) or 18.18%
Unclassified
6 measurement(s) or 16.22%0 member(s) or 0.00%
a7.3603—11.024 (10.3124)
b9.757—10.5516 (10.2368)
c7.044—13.931 (8.391)
alpha90
beta69.93—110.113 (102.2148)
gamma90
volume706.104—1384.72 (831.9187)

Based on 22 measurements
Baghdadite
Burpalite
Cuspidine
Janhaugite
Låvenite
Niocalite
Normandite
Titan-låvenite
Wöhlerite

Chemical context

Stoichiometric formulas

Wöhlerite Group
mindat.org
  • March 13, 2023X8(Si2O7)2W4X= Na+, Ca2+, Mn2+,Ti4+, Zr4+ and Nb5+ W= F-, O2-
mineralogy.rocks
  • Aug. 30, 2022A4(Si2O7)Z2

Elements recorded on EPMA

31
Ca
31
O
29
Si
28
F
24
Na
23
Zr
13
Ti
12
Mn
10
Nb
8
Fe
4
H
3
Mg
2
Hf
2
P
2
Y
1
Al
1
Ce
1
La
1
Lu
1
Nd
1
Pr
1
Ta

Physical properties

ColorColor entities, recognized using a custom trained NER model
6
  • brownish-yellow
  • honey yellow
  • lemon-yellow
  • pale yellowish
  • yellowish
6
  • light brown
  • orange-brown
  • pale brown
  • reddish brown
  • yellowish-brown
5
  • colorless
  • colourless
2
  • brownish-red
  • pale red
1
  • gray
1
    1
      Color noteOriginal color note from the source
      Colorless, tan, light brown, pale red.; Colorless to brownish-yellow, brown, brownish-red, orange-brown.; Colourless or yellowish; Colourless, pale brown, beige, pale yellowish; Honey yellow, wine yellow to sulfur yellow, light to dark yellow, brown, gray; Lemon-yellow; colourless in transmitted light; Reddish brown, golden-brown; Yellow, yellowish-brown, green
      StreakStreak entities, recognized using a custom trained NER model
      6
      • yellowish white
      • yellowish-white
      2
      • light brown
      • pale brown
      1
      • pale yellow
      Streak noteOriginal streak note from the source
      Light brown; White; Yellowish-white; pale brown; Yellowish white; pale yellow
      Lustre
      • Vitreous10
      • Waxy1
      • Sub-Vitreous1
      • Greasy3
      Fracture
      • Irregular/Uneven5
      • Splintery1
      • Conchoidal3
      Transparency
      • Transparent6
      • Translucent6
      Luminescence
      (not reported)
      Tenacity
      • brittle6
      • very brittle2
      Hardness