Koechlinite
A valid IMA mineral species - grandfathered
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About Koechlinite
Rudolf I. Koechlin
Formula:
Bi2MoO6
Colour:
Greenish yellow, white to light gray; greenish yellow in transmitted light
Lustre:
Silky
Specific Gravity:
8.26 (Calculated)
Crystal System:
Orthorhombic
Member of:
Name:
Named in 1914 by Waldemar Theodore Schaller in honor of Rudolf Ignatz Koechlin [November 11, 1862 Wien, Austria - February 11, 1939 Wien, Austria], Austrian mineralogist and Curator of the mineral collection of the Vienna Natural History Museum (former Hof-Museum), Vienna, Austria.
A rare secondary mineral occurring in the oxidation zones of Bi-Mo deposits.
The molybdate analogue of russellite.
The molybdate analogue of russellite.
Unique Identifiers
Mindat ID:
2235
Long-form identifier:
mindat:1:1:2235:0
IMA Classification of Koechlinite
Approved, 'Grandfathered' (first described prior to 1959)
IMA Formula:
Bi3+2Mo6+O6
First published:
1914
Classification of Koechlinite
4.DE.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
E : With medium-sized cations; with various polyhedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
E : With medium-sized cations; with various polyhedra
48.2.2.1
48 : ANHYDROUS MOLYBDATES AND TUNGSTATES
2 : A2XO4
48 : ANHYDROUS MOLYBDATES AND TUNGSTATES
2 : A2XO4
27.3.4
27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
27 : Sulphites, Chromates, Molybdates and Tungstates
3 : Molybdates
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Kcl | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Koechlinite
Silky
Transparency:
Transparent
Colour:
Greenish yellow, white to light gray; greenish yellow in transmitted light
Streak:
Pale greenish yellow
Tenacity:
Very brittle
Cleavage:
Perfect
On {010}, perfect on {0kl}, imperfect.
On {010}, perfect on {0kl}, imperfect.
Density:
8.26 g/cm3 (Calculated)
Optical Data of Koechlinite
Type:
Biaxial (-)
RI values:
nα = 2.52 nβ = 2.61 nγ = 2.67
Max. Birefringence:
δ = 0.150
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (76°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
No measured or calculated 2V is on file for this mineral, so the value used here (76°) is estimated from its recorded refractive indices and optic sign, not from a direct 2V measurement.
Dispersion:
none
Pleochroism:
Weak
Comments:
In shades of greenish yellow.
Comments:
2V measured = large.
Chemistry of Koechlinite
Mindat Formula:
Bi2MoO6
Element Weights:
Elements listed:
Crystallography of Koechlinite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Space Group:
Pna21
Cell Parameters:
a = 5.4822 Å, b = 16.1986 Å, c = 5.5091 Å
Ratio:
a:b:c = 0.338 : 1 : 0.34
Unit Cell V:
489.23 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals thin, square to rectangular plates striated parallel [010] and laths flattened on {010}; spheroidal aggregates of laths; massive or earthy incrustations.
Twinning:
{101} as twin plane, penetration and contact twins. Composition face {101} or {010} in contact twins.
Comment:
Pseudotetragonal; space group based on synthetic material.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
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Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
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2D | Stereo | Red-Blue | Red-Cyan
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View
CIF File Best | x | y | z | a | b | c
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Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
Console Off | On | Grey | Yellow
Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0009999 | Koechlinite | Teller R G, Brazdil J F, Grasselli R K, Jorgensen J D (1984) The structure of gamma-bismuth molybdate, Bi2MoO6, by powder neutron diffraction Acta Crystallographica C40 2001-2005 |  | 1984 | synthetic | 0 | 293 |
CIF Raw Data - click here to close
Epitaxy Comments:
Parallel growths with an unidentified orthorhombic mineral reported.
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.131 Å | (100) |
| 1.647 Å | (90) |
| 1.918 Å | (80) |
| 1.628 Å | (70) |
| 2.733 Å | (60) |
| 1.936 Å | (60) |
| 1.570 Å | (60) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47h : [Near-surface oxidized, dehydrated minerals] |
Type Occurrence of Koechlinite
Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts: #64801. U.S. National Museum of Natural History, Washington, D.C., USA: #R6411, 93646.
Other Language Names for Koechlinite
Dutch:Koechliniet
German:Koechlinit
Russian:Кехлинит
Simplified Chinese:钼铋矿
Spanish:Koechlinita
Traditional Chinese:鉬鉍礦
Relationship of Koechlinite to other Species
Member of:
Other Members of Koechlinite Group:
| Russellite | Bi2WO6 | Orth. mm2 : Pca21 |
| Tungstibite | Sb3+2WO6 | Orth. 222 |
Common Associates
Associations Based on Photo Data:
| 11 photos of Koechlinite associated with Bismuthinite | Bi2S3 |
| 8 photos of Koechlinite associated with Quartz | SiO2 |
| 5 photos of Koechlinite associated with Bismutite | (BiO)2CO3 |
| 2 photos of Koechlinite associated with Wolframite Group | |
| 2 photos of Koechlinite associated with Muscovite | KAl2(AlSi3O10)(OH)2 |
| 2 photos of Koechlinite associated with Covellite | CuS |
| 2 photos of Koechlinite associated with Molybdenite | MoS2 |
| 2 photos of Koechlinite associated with Anglesite | PbSO4 |
| 2 photos of Koechlinite associated with Russellite | Bi2WO6 |
| 2 photos of Koechlinite associated with Native Bismuth | Bi |
Related Minerals - Strunz-mindat Grouping
| 4.DE. | Colchesterite | Bi3+2Mo6+2O9 |
| 4.DE. | Pertoldite | GeO2 |
| 4.DE. | Ziroite | ZrO2 |
| 4.DE.05 | Downeyite | SeO2 |
| 4.DE.10 | Koragoite | (Mn2+,Fe3+)3(Nb,Ta,Ti)2(Nb,Mn)2(W,Ta)2O20 |
| 4.DE.15 | Russellite | Bi2WO6 |
| 4.DE.15 | Tungstibite | Sb3+2WO6 |
| 4.DE.20 | Tellurite | TeO2 |
| 4.DE.25 | Paratellurite | TeO2 |
| 4.DE.30 | Bismutotantalite | BiTaO4 |
| 4.DE.30 | Stibiotantalite | Sb3+TaO4 |
| 4.DE.30 | Cervantite | Sb3+Sb5+O4 |
| 4.DE.30 | Bismutocolumbite | BiNbO4 |
| 4.DE.30 | Stibiocolumbite | SbNbO4 |
| 4.DE.30 | Clinocervantite | Sb3+Sb5+O4 |
| 4.DE.35 | Baddeleyite | ZrO2 |
| 4.DE.40 | Billwiseite | Sb3+5Nb3WO18 |
| 4.DE.45 | Kyawthuite | Bi3+Sb5+O4 |
Other Information
Notes:
Readily soluble in HCl, less so in HNO3.
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 Koechlinite
mindat.org URL:
https://www.mindat.org/min-2235.html
Please feel free to link to this page.
Please feel free to link to this page.
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External Links:
Mineral Dealers:
References for Koechlinite
Reference List:
Larsen, E.S.; Berman, H. (1934) The microscopic determination of the nonopaque minerals. Bulletin of the US Geological Survey Vol. 848. US Geological Survey p.1-266. doi:10.3133/b848 p.212
Frondel, Clifford (1943) New data on agricolite, bismoclite, koechlinite, and the bismuth arsenates. American Mineralogist, 28 (9-10) 536-540
Zemann, Josef (1956) Die Kristallstruktur von Koechlinit, Bi2MoO6. Heidelberger Beiträge zur Mineralogie und Petrographie, 5 (2). 139-145 doi:10.1007/bf01129682
van den Elzen, A. F., Rieck, G. D. (1973) Redetermination of the structure of Bi2MoO6, koechlinite. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 29 (11) 2436-2438 doi:10.1107/s0567740873006801
Localities for Koechlinite
Showing 47 localities.
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Australia | |
| Palache et al. (1951) |
| Rankin et al. (2002) +1 other reference |
| Elliott et al. (2026) | |
| Sharpe et al. (2004) | |
| Clissold (2007) | |
| Petrella (2015) |
| Elliott et al. (2025) |
| R Bottrill |
| Birch (2001) |
| Museum Victoria Mineralogy Collection |
| Palache et al. (1951) |
| Hodge (1970) |
China | |
| www.minsocam.org (2009) |
Czech Republic | |
| Sejkora et al. (2006) |
| Jiří Sejkora - Sekundární minerály ... |
| Samples was analysed by P. Pauliš. |
| J.Sejkora | |
Europe | |
| Paulis et al. (2003) |
Germany | |
| Walenta (1992) +1 other reference |
| |
| Journal of the Washington Academy of Science (1914) +2 other references | |
| Massanek et al. (2005) |
| Witzke et al. (2007) |
| Witzke et al. (2007) |
Italy | |
| Gentile et al. (2023) |
| Gentile et al. (2023) |
| Orlandi et al. (2011) +1 other reference |
| Orlandi et al. (2005) | |
| - (n.d.) |
Japan | |
| 浜地忠男 (1961) +1 other reference |
| Sadanaga et al. (1974) |
Kazakhstan | |
| Jermolenko (2002) |
| Pavel M. Kartashov (n.d.) |
Mexico | |
| dan weinrich |
Poland | |
| Kozłowski et al. (2016) |
| Mochnacka et al. (2015) +2 other references |
South Africa | |
| S. Weinert (2006) +1 other reference |
| Cairncross et al. (1995) |
Spain | |
| Rewitzer et al. (2018) |
| Calvo Rebollar (2009) |
UK | |
| M.Wirth collection |
USA | |
| Anthony et al. (1995) |
| Dunning et al. (1998) |
| Dunning et al. (2005) | |
| Freeport-McMoRan |
| Cooper et al. (1991) |
| Wolff et al. (2014) |
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Daniel Mine, Neustädtel, Schneeberg, Erzgebirgskreis, Saxony, Germany