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Bornhardtite

A valid IMA mineral species - grandfathered
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Formula:
Co2+Co3+2Se4
Colour:
Rose-red
Hardness:
4
Specific Gravity:
6.166 (Calculated)
Crystal System:
Isometric
Name:
For Dr. Friedrich Wilhelm Conrad Eduard Bornhardt (20 April 1864 Braunschweig - 2 December 1946 Goslar), German geologist, engineer and explorer, and was Director of the Berlin College of Mines (Bergakademie) from 1907 to 1916.
Se analogue of Linnaeite.
Current status "grandfathered" but considered questionable by Bosi et al. (2019).
A mineral that appears to never have been analyzed; compare tyrrellite.


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Unique IdentifiersHide

Mindat ID:
726
Long-form identifier:
mindat:1:1:726:7

IMA Classification of BornhardtiteHide

Classification of BornhardtiteHide

Strunz-mindat (2025):
2.DA.05

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
D : Metal Sulfides, M: S = 3 :4 and 2:3
A : M:S = 3:4
Dana 8th ed.:
2.10.1.5

2 : SULFIDES
10 : AmBnXp, with (m+n):p = 3:4
Hey's CIM Ref.:
3.10.5

3 : Sulphides, Selenides, Tellurides, Arsenides and Bismuthides (except the arsenides, antimonides and bismuthides of Cu, Ag and Au, which are included in Section 1)
10 : Sulphides etc. of Co

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference
BhdIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Physical Properties of BornhardtiteHide

Transparency:
Opaque
Colour:
Rose-red
Hardness:
4 on Mohs scale
Density:
6.166 g/cm3 (Calculated)

Optical Data of BornhardtiteHide

Reflectivity:
WavelengthR1 (%)
400nm41.3%
420nm42.8%
440nm44.3%
460nm45.4%
480nm46.4%
500nm47.2%
520nm47.8%
540nm48.4%
560nm49.2%
580nm49.2%
600nm49.7%
620nm50.2%
640nm50.8%
660nm51.4%
680nm52.0%
700nm52.7%


Graph shows reflectance levels at different wavelengths (in nm). Peak reflectance is 52.7%.

Chemistry of BornhardtiteHide

Mindat Formula:
Co2+Co3+2Se4
Element Weights:
Element% weight
Se64.112 %
Co35.888 %

Calculated from ideal end-member formula.
Elements listed:
Co, Se - search for minerals with similar chemistry

Crystallography of BornhardtiteHide

Crystal System:
Isometric
Class (H-M):
m3m (4/m 3 2/m) - Hexoctahedral
Space Group:
Fd3m
Setting:
Fd3m
Cell Parameters:
a = 10.2(2) Å
Unit Cell V:
1,061.21 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Massive

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
2.7 Å(100)
2.4 Å(100)
2.3 Å(100)
2.2 Å(100)
2.0 Å(100)
1.96 Å(100)
1.42 Å(100)
Comments:
Trogtal quarry, Germany.

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
High-𝑇 alteration and/or metamorphism
33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12])
Geological Setting:
Hydrothermal

Type Occurrence of BornhardtiteHide

Other Language Names for BornhardtiteHide

Relationship of Bornhardtite to other SpeciesHide

Member of:
Bornhardtite Subgroup > Seleniospinel Group > Spinel Supergroup
Other Members of Bornhardtite Subgroup:
TrüstedtiteNi3Se4Iso.

Common AssociatesHide

Associated Minerals Based on Photo Data:
1 photo of Bornhardtite associated with TrogtaliteCoSe2

Related Minerals - Strunz-mindat GroupingHide

2.DA.FerrodimolybdeniteFeMo2S4Mon. 2/m : B2/b
2.DA.ZaykoviteRh3Se4Mon. 2/m : B2/m
2.DA.EzochiiteCu+(Rh3+Pt4+)S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.GrimmiteNiCo2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.ZolenskyiteFeCr2S4Mon. 2/m : B2/m
2.DA.05ShiranuiiteCu+(Rh3+Rh4+)S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05FletcheriteCuNi2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05Florensovite(Cu,Zn)Cr1.5Sb0.5S4Iso. m3m (4/m 3 2/m)
2.DA.05SiegeniteCoNi2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05CadmoinditeCdIn2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05KalininiteZnCr2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05ViolariteFe2+Ni3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05NickeltyrrelliteCuNi2Se4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05LinnaeiteCo2+Co3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05CarrolliteCuCo2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05Cuproiridsite(Cu,Fe)Ir2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05Cuprorhodsite(Cu1+0.5Fe3+0.5)Rh3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05BerndlehmanniteCu(CrV)S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05PolydymiteNi2+Ni3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05TrüstedtiteNi3Se4Iso.
2.DA.05DaubréeliteFe2+Cr3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05CuprokalininiteCuCr2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05GreigiteFe2+Fe3+2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05JoegoldsteiniteMnCr2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05TyrrelliteCu(Co,Ni)2Se4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05InditeFeIn2S4Iso. m3m (4/m 3 2/m) : Fd3m
2.DA.05XingzhongitePb2+Ir3+2S4Iso.
2.DA.05MalaniteCu1+(Ir3+Pt4+)S4Iso. m3m (4/m 3 2/m)
2.DA.10RhodostanniteCu1+(Fe2+0.5Sn4+1.5)S4Tet. 4/m : I41/a
2.DA.10ToyohaiteAg1+(Fe2+0.5Sn4+1.5)S4Tet. 4/m : I41/a
2.DA.15BrezinaiteCr3S4Mon. 2/m
2.DA.15Heideite(Fe,Cr)1.15(Ti,Fe)2S4Mon. 2/m
2.DA.20KonderiteCu3Pb(Rh,Pt,Ir)8S16Hex. 6/m : P6/m
2.DA.20InaglyiteCu3Pb(Ir,Pt)8S16Hex.
2.DA.25Kingstonite(Rh,Ir,Pt)3S4Mon. 2/m : B2/m

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for BornhardtiteHide

References for BornhardtiteHide

Localities for BornhardtiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Argentina
 
  • Mendoza Province
    • Luján de Cuyo department
      • Cacheuta District
Grundmann et al. (2018)
Mineralogical Society of America - ...
Canada
 
  • Saskatchewan
Mineralogical Society of America - ...
Germany (TL)
 
  • Lower Saxony
    • Goslar District
      • Harz (Landkreis Goslar)
Ramdohr et al. (1955) +3 other references
    • Göttingen District
      • Harz (Landkreis Göttingen)
Weiß (1990)
  • Saxony-Anhalt
    • Mansfeld-Südharz
      • Mansfeld
Tischendorf (1969) +1 other reference
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