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MINERAL CLASSIFICATION / SYSTEMATIK der MINERALE

           based on E.H. Nickel & M.C. Nichols (2009), H. Strunz & E.H. Nickel (2001),
           revised by Thomas Witzke (2023)



6. BORATES



6.B: Soroborates


6.BA. Soro-diborates with double triangles B2(O,OH)5, (2Δ)
 
6.BA.005. Suanite
 
Suanite Mg2(B2O5) tric., P1 A


 
6.BA.010. Shimazakiite
 
Shimazakiite Ca2(B2O5) mon., P21/c IMA 2010-085a

Shimazakiite polytypes: Shimazakiite-4M (mon., P21/c), Shimazakiite-4O (orth., P212121).


 
6.BA.015. Kurchatovite group
 
Kurchatovite CaMg(B2O5) orth., Pca21 IMA 1965-034
Clinokurchatovite CaMg(B2O5) mon., P21/c IMA 1982-017


 
6.BA.020. Szaibelyite group
 
Szaibelyite Mg2(B2O4OH)(OH) mon., P21/a FOTO A
Sussexite Mn2(B2O4OH)(OH) mon., P21/a G


 
6.BA.025. Wiserite
 
Wiserite Mn14(B2O5)4(OH)8·(Si,Mg)(O,OH)4Cl tetr., P4/n G



 
 
6.BB. Soro-diborates with triangle + tetrahedron, B2O4(OH)2, )
 
6.BB.005. Krasnoshteinite
 
Krasnoshteinite Al8[B2O4(OH)2](OH)16Cl4·7H2O mon., P21 IMA 2018-077



 
 
6.BC. Soro-diborates with double tetrahedra B2O(OH)6, (2)
 
6.BC.005. Pinnoite
 
Pinnoite Mg(B2O(OH)6) tetr., P42 FOTO G


 
6.BC.010. Pentahydroborite
 
Pentahydroborite Ca(B2O(OH)6)·2H2O tric, P1 A



 
 
 

G = Grandfathered minerals: original description preceded the establishment of the CNMNC in 1959, and generally regarded as a valid species
A or IMA No. = Minerals approved by the CNMNC
Rd = Redefinition of the mineral approved by the CNMNC
Rn = Renamed with approval by the CNMNC
Q = Questionable mineral



Classification principles:
The classification is based on the linkage of borate triangles (BO3), symbol Δ, and borate tetrahedra (BO4), symbol , to form fundamental building blocks (FBB) (see in Grice et al., 1999). According to the polymerization of the borate groups the subdivision is made now into Neso-, Soro-, Cyclo-, Ino-, Phyllo- and Tecto-borates, adapted from the well-known subdivision of the Silicates class and following the recommendation in Mills et al. (2009) on the standardisation of mineral group hierarchies.
Soroborates are minerals with isolated clusters of connected borate groups. This definition would be fulfilled also by Cycloborates with isolated clusters of borate groups in ring-shaped arrangement. In fact, these ring-shaped arrangements are classified in Grice et al. (1999) as Soroborates, and Cycloborates are not mentioned. In the classification here the Cycloborates are treated as a separate subclass to adapt the classification of the Silicates (Mills et al., 2009). Therefore, only minerals with clusters of connected borate groups with a linear shape are classified here as Soroborates. In natural minerals only linear arrangements of two connected borate groups exist, larger linear units with three or more connected borate groups are not known up to now.

The further subdivision of the subclass "6.B: Soroborates" is made according to the type of the connected borate groups into 6.BA. Soro-diborates with double triangles B2(O,OH)5, (2Δ); 6.BB. Soro-diborates with triangle + tetrahedron, B2O4(OH)2, (Δ); 6.BC. Soro-diborates with double tetrahedra B2O(OH)6, (2).

Further classification:
6.BA. Soro-diborates with double triangles B2(O,OH)5, (2Δ): Without other anions or water; with other anions or water.
6.BB. Soro-diborates with triangle + tetrahedron, B2O4(OH)2, ): Only one mineral.
6.BC. Soro-diborates with double tetrahedra B2O(OH)6, (2): Without other anions or water; with other anions or water.


Reference:
Grice, J.D.; Burns, P.C. & Hawthorne, F.C. (1999): Borate Minerals. II. A hierarchy of structures based upon the borate fundamental building block. Can. Min. 37, 731-762.
Mills, S.J.; Hatert, F.; Nickel, E. & Ferraris, G. (2009): The standardisation of mineral group hierarchies: application to recent nomenclature proposals. Eur. J. Mineral. 21, 1073-1080.


To distinguish from classical Strunz numbering, on hierarchical "group" level, a numbering with 3 digits is used, like "6.BA.005. Suanite", instead of 2 digits (like "6.BA.05.") in the Strunz system.



© Thomas Witzke (2023)


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