Large (up to 1.8 cm) yellow londonite crystals associated with rubellite tourmaline. Londonite is an unusual caesium-rich heptaborate.^[1]

The borate minerals are minerals which contain a borate anion group. The borate (BO₃) units may be polymerised similar to the SiO₄ unit of the silicate mineral class. This results in B₂O₅, B₃O₆, B₂O₄ anions as well as more complex structures which include hydroxide or halogen anions.^[2] The [B(O,OH)₄]⁻ anion exists too.

Many borate minerals, such as borax, colemanite, and ulexite, are salts: soft, readily soluble, and found in evaporite contexts. However, some, such as boracite, are hard and resistant to weathering, more similar to the silicates.

There are over 100 different borate minerals.^[2][3] Borate minerals include:

• 
  Kernite Na₂B₄O₆(OH)₂·3H₂O


• 
  Borax Na₂B₄O₅(OH)₄·8H₂O


• 
  Ulexite NaCaB₅O₆(OH)₆·5H₂O


• 
  Colemanite CaB₃O₄(OH)₃·H₂O


• 
  Boracite Mg₃B₇O₁₃Cl


• 
  Painite CaZrAl₉O₁₅(BO₃)

Nickel–Strunz Classification -06- Borates[edit]

IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). This list uses it to modify the Classification of Nickel–Strunz (mindat.org, 10 ed, pending publication).

• Abbreviations:
  
  • "*" - discredited (IMA/CNMNC status).
  
  
  • "?" - questionable/doubtful (IMA/CNMNC status).
  
  
  • "REE" - Rare-earth element (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu)
  
  
  • "PGE" - Platinum-group element (Ru, Rh, Pd, Os, Ir, Pt)
  
  
  • 03.C Aluminofluorides, 06 Borates, 08 Vanadates (04.H V^[5,6] Vanadates), 09 Silicates:
    
    • Neso: insular (from Greek νησος nēsos, island)
    
    
    • Soro: grouping (from Greek σωροῦ sōros, heap, mound (especially of corn))
    
    
    • Cyclo: ring
    
    
    • Ino: chain (from Greek ις [genitive: ινος inos], fibre)
    
    
    • Phyllo: sheet (from Greek φύλλον phyllon, leaf)
    
    
    • Tekto: three-dimensional framework
    
    
  
  


• Nickel–Strunz code scheme: NN.XY.##x
  
  • NN: Nickel–Strunz mineral class number
  
  
  • X: Nickel–Strunz mineral division letter
  
  
  • Y: Nickel–Strunz mineral family letter
  
  
  • ##x: Nickel–Strunz mineral/group number, x add-on letter
  
  

Class: borates[edit]

• 06. Alfredstelznerite
  


• 06.A Monoborates
  
  • 06.AA BO₃, without additional anions; 1(D): 05 Sassolite; 15 Nordenskioldine, 15 Tusionite; 35 Jimboite, 35 Kotoite; 40 Takedaite
    
  
  
  • 06.AB BO₃, with additional anions; 1(D) + OH, etc.: 05 Hambergite, 10 Berborite, 15 Jeremejevite; 20 Warwickite, 20 Yuanfuliite; 25 Karlite; 30 Azoproite, 30 Bonaccordite, 30 Fredrikssonite, 30 Ludwigite, 30 Vonsenite; 35 Pinakiolite; 40 Blatterite, 40 Orthopinakiolite, 40 Takeuchiite, 40 Chestermanite; 45 Hulsite, 45 Magnesiohulsite, 45 Aluminomagnesiohulsite; 50 Hydroxylborite, 50 Fluoborite; 55 Shabynite, 55 Wightmanite; 60 Gaudefroyite, 65 Sakhaite, 70 Harkerite; 75 IMA2008-060, 75 Pertsevite; 80 Jacquesdietrichite, 85 Painite
    
  
  
  • 06.AC B(O,OH)₄, without and with additional anions; 1(T), 1(T)+OH, etc.: 05 Sinhalite, 10 Pseudosinhalite; 15 Behierite, 15 Schiavinatoite; 20 Frolovite, 25 Hexahydroborite, 30 Henmilite, 35 Bandylite, 40 Teepleite, 45 Moydite-(Y), 50 Carboborite, 55 Sulfoborite, 60 Luneburgite, 65 Seamanite, 70 Cahnite
    
  
  


• 06.H Unclassified Borates
  
  • 06.HA Unclassified borates: 05 Chelkarite, 10 Braitschite-(Ce), 15 Satimolite, 20 Iquiqueite, 25 Wardsmithite, 30 Korzhinskite, 35 Halurgite, 40 Ekaterinite, 45 Vitimite, 50 Canavesite, 55 Qilianshanite
    

Subclass: nesoborates[edit]

• 06.BA Neso-diborates with double triangles B₂(O,OH)₅; 2(2D); 2(2D) + OH, etc.: 05 Suanite; 10 Clinokurchatovite, 10 Kurchatovite; 15 Sussexite, 15 Szaibelyite; 20 Wiserite
  


• 06.BB Neso-diborates with double tetrahedra B₂O(OH)₆; 2(2T): 05 Pinnoite, 10 Pentahydroborite
  


• 06.CA Neso-triborates: 10 Ameghinite, 15 Inderite, 20 Kurnakovite, 25 Inderborite, 30 Meyerhofferite, 35 Inyoite, 40 Solongoite, 45 Peprossiite-(Ce), 50 Nifontovite, 55 Olshanskyite
  


• 06.DA Neso-tetraborates: 10 Borax, 15 Tincalconite, 20 Hungchaoite; 25 Fedorovskite, 25 Roweite; 30 Hydrochlorborite, 35 Uralborite; 40 Numanoite, 40 Borcarite, 60 Fontarnauite
  


• 06.EA Neso-pentaborates: 05 Sborgite; 10 Ramanite-(Rb), 10 Ramanite-(Cs), 10 Santite; 15 Ammonioborite, 25 Ulexite
  


• 06.FA Neso-hexaborates: 05 Aksaite, 10 Mcallisterite, 15 Admontite, 20 Rivadavite, 25 Teruggite
  

Subclass: inoborates[edit]

• 06.BC Ino-diborates with triangles and/or tetrahedra: 10 Calciborite, 10 Aldzhanite*; 15 Vimsite; 20 Sibirskite, 20 Parasibirskite
  


• 06.CB Ino-triborates: 10 Colemanite, 15 Hydroboracite, 20 Howlite, 25 Jarandolite
  


• 06.DB Ino-tetraborates: 05 Kernite
  


• 06.EB Ino-pentaborates: 05 Larderellite, 10 Ezcurrite, 15 Probertite, 20 Tertschite, 25 Priceite
  


• 06.FB Ino-hexaborates: 05 Aristarainite, 10 Kaliborite
  

Subclass: phylloborates[edit]

• 06.CC Phyllo-triborates: 05 Johachidolite
  


• 06.EC Phyllo-pentaborates: 05 Biringuccite, 05 Nasinite; 10 Gowerite; 15 Veatchite, 15 Veatchite-A, 15 Veatchite-p; 20 Volkovskite, 25 Tuzlaite, 30 Heidornite, 35 Brianroulstonite
  


• 06.FC Phyllo-hexaborates: 05 Nobleite, 05 Tunellite, 05 Balavinskite?; 10 Strontioborite; 15 Ginorite, 15 Strontioginorite; 20 Fabianite
  


• 06.GB Phyllo-nonborates, etc.: 05 Studenitsite, 10 Penobsquisite, 15 Preobrazhenskite, 20 Walkerite
  

Subclass: tektoborates[edit]

• 06.BD Tektodiborates with tetrahedra: 05 Santarosaite
  


• 06.DD Tekto-tetraborates: 05 Diomignite
  


• 06.ED Tekto-pentaborates: 05 IMA2007-047, 05 Tyretskite, 05 Hilgardite, 05 Kurgantaite
  


• 06.GA Tekto-heptaborates: 05 Boracite, 05 Chambersite, 05 Ericaite; 10 Congolite, 10 Trembathite
  


• 06.GC Tekto-dodecaborates: 05 Rhodizite, 05 Londonite
  


• 06.GD Mega-tektoborates: 05 Ruitenbergite, 05 Pringleite; 10 Metaborite
  

See also[edit]

• Classification of minerals - Non-silicates


• Classification of minerals - Silicates

References[edit]

External links[edit]

Media related to Londonite at Wikimedia Commons