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. 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. Borate minerals include:
Kernite Na2B4O6(OH)3·3H2O
Borax Na2B4O5(OH)4·8H2O
Ulexite NaCaB5O6(OH)6·5H2O
Colemanite CaB3O4(OH)3·H2O
Boracite Mg3B7O13Cl
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
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
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
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
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
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
