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Dorrite
A valid IMA mineral species
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About Dorrite
John A. Dorr
Formula:
Ca4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)
Idealized formula for Kopeisk material: Ca4Mg4Fe3+8[Al8Si4O20]
Colour:
red-brown, brown-black, dark brown
Lustre:
Sub-Metallic
Hardness:
5½
Specific Gravity:
3.059 (Calculated)
Crystal System:
Triclinic
Member of:
Name:
Named by Michael A. Cosca, Roland R. Rouse, and Eric J. Essene in 1987 in honor of John A. "Jack" Dorr, Jr. (1922/3 - 8 April 1986), Professor of Geology, University of Michigan, Ann Arbor, Michigan, USA, in recognition of his geologic research in Wyoming.
Stable in strongly oxidizing, high-temperature low-pressure environments.
Site occupancy for dorrite from Kopeisk (Shchipalkina et al., 2016), is: M1: (Fe3+,Mg); M2: (Fe3+,Mg); M3: 2(Fe3+,Mg); M4: 2(Fe3+,Mg); M5: 2Mg; M6: 2(Mg,Fe3+); M7: 2(Fe3+,Al); M8: 2Ca; M9: 2Ca; T1: 2(Si,Al); T2: 2(Si,Al); T3: 2Al; T4: 2Si; T5: 2(Al,Fe3+); T6: 2(Al,Fe3+).
Site occupancy for dorrite from Kopeisk (Shchipalkina et al., 2016), is: M1: (Fe3+,Mg); M2: (Fe3+,Mg); M3: 2(Fe3+,Mg); M4: 2(Fe3+,Mg); M5: 2Mg; M6: 2(Mg,Fe3+); M7: 2(Fe3+,Al); M8: 2Ca; M9: 2Ca; T1: 2(Si,Al); T2: 2(Si,Al); T3: 2Al; T4: 2Si; T5: 2(Al,Fe3+); T6: 2(Al,Fe3+).
Unique Identifiers
Mindat ID:
1313
Long-form identifier:
mindat:1:1:1313:6
Similar Names
IMA Classification of Dorrite
Approved
IMA Formula:
Ca4(Mg3Fe3+9)O4[Si3Al8Fe3+O36]
Approval year:
1987
First published:
1988
Classification of Dorrite
9.DH.40
9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si4O12
9 : SILICATES (Germanates)
D : Inosilicates
H : Inosilicates with 4-periodic single chains, Si4O12
69.2.1a.2
69 : INOSILICATES Chains with Side Branches or Loops
2 : Chains with Side Branches or Loops with P>2
69 : INOSILICATES Chains with Side Branches or Loops
2 : Chains with Side Branches or Loops with P>2
16.23.2
16 : Silicates Containing Aluminum and other Metals
23 : Aluminosilicates of Fe, Ca, and Mg
16 : Silicates Containing Aluminum and other Metals
23 : Aluminosilicates of Fe, Ca, and Mg
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 |
|---|---|---|
| Dor | 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 Dorrite
Sub-Metallic
Transparency:
Opaque
Colour:
Red-brown, brown-black, dark brown
Streak:
Brownish grey
Hardness:
5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Distinct/Good
Good on {010} and {001}.
Good on {010} and {001}.
Fracture:
Irregular/Uneven
Density:
3.059 g/cm3 (Calculated)
Optical Data of Dorrite
Type:
Biaxial (-)
RI values:
nα = 1.82(1) nβ = 1.84(1) nγ = 1.86(1)
2V:
Measured: 90° , Calculated: 88°
Max. Birefringence:
δ = 0.040
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.
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.
Dispersion:
small
Pleochroism:
Strong
Comments:
X = red-orange brown; Y = yellowish brown; Z = greenish brown.
Chemistry of Dorrite
Mindat Formula:
Ca4(Mg3Fe3+9)O4(Si3Al8Fe3+O36)
Idealized formula for Kopeisk material: Ca4Mg4Fe3+8[Al8Si4O20]
Idealized formula for Kopeisk material: Ca4Mg4Fe3+8[Al8Si4O20]
Element Weights:
Common Impurities:
Ti,Cr,Mn,Na,K
Crystallography of Dorrite
Crystal System:
Triclinic
Cell Parameters:
a = 10.5 Å, b = 10.89 Å, c = 9.91 Å
α = 106.26°, β = 95.16°, γ = 124.75°
α = 106.26°, β = 95.16°, γ = 124.75°
Ratio:
a:b:c = 0.964 : 1 : 0.91
Unit Cell V:
847.91 ų (Calculated from Unit Cell)
Morphology:
As anhedral to prismatic grains, to 0.1 mm; some grains exhibit hopper and skeletal habits
Twinning:
Twinned by two-fold rotation about the pseudomonoclinic [010] axis.
Comment:
Point Group: 1 or 1 . ; Space Group: P1 or P1 .
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 2.971 Å | (100) |
| 2.558 Å | (80) |
| 2.515 Å | (80) |
| 2.125 Å | (60) |
| 1.511 Å | (30) |
| 1.482 Å | (30) |
| 8.1 Å | (20) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47h : [Near-surface oxidized, dehydrated minerals] | |
| Stage 10a: Neoproterozoic oxygenation/terrestrial biosphere | <0.6 |
| 50 : Coal and/or oil shale minerals | <0.36 |
| 51 : Pyrometamorphic minerals (see also #54 and #56) | <0.36 |
| Stage 10b: Anthropogenic minerals | <10 Ka |
| 54 : Coal and other mine fire minerals (see also #51 and #56) | |
| 56 : Slag and smelter minerals (see also #51 and #55) |
Type Occurrence of Dorrite
Place of Conservation of Type Material:
University of Michigan, Ann Arbor, Michigan; National Museum of Natural History, Washington, D.C., USA (163357).
Associated Minerals at Type Locality:
Synonyms of Dorrite
Other Language Names for Dorrite
Relationship of Dorrite to other Species
Member of:
Other Members of Rhönite Group:
| Høgtuvaite | Ca4[Fe2+6Fe3+6]O4[Si8Be2Al2O36] | Tric. 1 : P1 |
| Kuratite | Ca2(Fe2+5Ti)O2[Si4Al2O18] | Tric. 1 : P1 |
| 'Leucorhönite' | Ca2(Mg,Fe3+,Al)6(Si,Al)6O20 | Tric. |
| Makarochkinite | (Ca,Na)4[Fe2+8Fe3+2Ti2]O4[Si8Be2Al2O36] | Tric. 1 : P1 |
| Rhönite | Ca4[Mg8Fe3+2Ti2]O4[Si6Al6O36] | Tric. 1 : P1 |
| Serendibite | Ca4[Mg6Al6]O4[Si6B3Al3O36] | Tric. 1 : P1 |
| Welshite | Ca4Mg9Sb3O4[Si6Be3AlFe2O36] | Tric. 1 : P1 |
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 9.DH. | Devilliersite | Ca4Ca2Fe3+10O4[(Fe3+10Si2)O36] |
| 9.DH. | 'Gageite-2M' | (Mn,Mg,Zn)42Si16O54(OH)40 |
| 9.DH. | Bavsiite | Ba2V2O2[Si4O12] |
| 9.DH. | Yuzuxiangite | Sr3Fe3+(Si2O6)2(OH) · 3H2O |
| 9.DH. | Louisfuchsite | Ca2(Mg4Ti2)(Al4Si2)O20 |
| 9.DH.05 | Leucophanite | NaCaBeSi2O6F |
| 9.DH.10 | Ohmilite | Sr3(Ti,Fe3+)(Si4O12)(O,OH) · 2-3H2O |
| 9.DH.15 | Haradaite | SrVSi2O7 |
| 9.DH.15 | Suzukiite | BaVSi2O7 |
| 9.DH.20 | Shcherbakovite | (K,Ba)KNa(Ti,Nb)2(Si4O12)O2 |
| 9.DH.20 | Batisite | BaNaNaTi2(Si4O12)O2 |
| 9.DH.20 | Noonkanbahite | BaKNaTi2(Si4O12)O2 |
| 9.DH.25 | Taikanite | Sr3BaMn2+2(Si4O12)O2 |
| 9.DH.30 | Krauskopfite | BaSi2O5 · 3H2O |
| 9.DH.35 | Gageite | Mn21(Si4O12)2O3(OH)20 |
| 9.DH.35 | Balangeroite | (Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)40 |
| 9.DH.40 | Kuratite | Ca2(Fe2+5Ti)O2[Si4Al2O18] |
| 9.DH.40 | Aenigmatite | Na4[Fe2+10Ti2]O4[Si12O36] |
| 9.DH.40 | Serendibite | Ca4[Mg6Al6]O4[Si6B3Al3O36] |
| 9.DH.40 | Rhönite | Ca4[Mg8Fe3+2Ti2]O4[Si6Al6O36] |
| 9.DH.40 | Khesinite | Ca4(Mg3Fe3+9)O4(Fe3+9Si3)O36 |
| 9.DH.40 | 'UM1991-29-SiO:FeMgNa' | Na4(Mg5Fe3+7)O4[Si9Fe3+3O36] |
| 9.DH.40 | Høgtuvaite | Ca4[Fe2+6Fe3+6]O4[Si8Be2Al2O36] |
| 9.DH.40 | 'Leucorhönite' | Ca2(Mg,Fe3+,Al)6(Si,Al)6O20 |
| 9.DH.40 | Welshite | Ca4Mg9Sb3O4[Si6Be3AlFe2O36] |
| 9.DH.40 | Wilkinsonite | Na2Fe2+4Fe3+2(Si6O18)O2 |
| 9.DH.40 | Krinovite | Na2Mg4Cr3+2(Si6O18)O2 |
| 9.DH.40 | Makarochkinite | (Ca,Na)4[Fe2+8Fe3+2Ti2]O4[Si8Be2Al2O36] |
| 9.DH.45 | Sapphirine | Mg4(Mg3Al9)O4[Si3Al9O36] |
| 9.DH.50 | Khmaralite | (Mg,Al,Fe)16[(Al,Si,Be)12O36]O4 |
| 9.DH.55 | 'UM1988-26-SiO:AlMg' | Mg4Al2O[Si3Al2O15] |
| 9.DH.55 | Surinamite | (Mg,Fe)3Al4BeSi3O16 |
| 9.DH.60 | Deerite | Fe2+6Fe3+3(Si6O17)O3(OH)5 |
| 9.DH.65 | Taneyamalite | (Na,Ca)Mn2+12(Si,Al)12(O,OH)44 |
| 9.DH.65 | Howieite | Na(Fe2+,Fe3+,Al,Mg)12(Si6O17)2(O,OH)10 |
| 9.DH.70 | Johninnesite | Na2Mn2+9Mg7(OH)8[AsO4]2[Si6O17]2 |
| 9.DH.75 | Agrellite | NaCa2Si4O10F |
Other Information
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 Dorrite
mindat.org URL:
https://www.mindat.org/min-1313.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Dorrite
Reference List:
Cosca, Michael A., Rouse, Roland C., Essene, Eric J. (1988) Dorrite [Ca2(Mg2Fe3+4)(Al4Si2)O20], a new member of the aenigmatite group from a pyrometamorphic melt-rock. American Mineralogist, 73 (11-12) 1440-1448
Jensen, B. B. (1996) Solid solution among members of the aenigmatite group. Mineralogical Magazine, 60 (403) 982-986 doi:10.1180/minmag.1996.060.403.14
Kunzmann, Thomas (1999) The aenigmatite-rhönite mineral group. European Journal of Mineralogy, 11 (4) 743-756 doi:10.1127/ejm/11/4/0743
Grew, E. S.; Hålenius, U.; Pasero, M.; Barbier, J. (2008) Recommended nomenclature for the sapphirine and surinamite groups (sapphirine supergroup). Mineralogical Magazine, 72 (4). p.839-876. doi:10.1180/minmag.2008.072.4.839
Shchipalkina, Nadezhda V., Zubkova, Natalia V., Pekov, Igor V., Koshlyakova, Natalia N. (2016) Dorrite from Kopeisk, South Urals, Russia: crystal structure and cation ordering. Neues Jahrbuch für Mineralogie - Abhandlungen Journal of Mineralogy and Geochemistry, 193 (3) 275-282 doi:10.1127/njma/2016/0001
Shchipalkina, Nadezhda V., Pekov, Igor V., Chukanov, Nikita V., Koshlyakova, Natalya N., Ternes, Bernd, Schüller, Willi (2019) Crystal chemistry of dorrite from the Eifel volcanic region, Germany, and chemical variations in the khesinite-dorrite-rhönite-kuratite solid-solution system. Mineralogy and Petrology, 113 (2) 249-259 doi:10.1007/s00710-018-0645-0
Localities for Dorrite
Showing 20 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.
Germany | |
| Blaß et al. (2015) |
| Blaß et al. (2015) |
| Kunzmann (1999) +1 other reference |
| Blaß et al. (2015) | |
| Blaß et al. (2015) |
| Shchipalkina et al. (2019) |
| Blaß et al. (2014) |
Israel | |
| Britvin et al. (2021) +1 other reference |
| Krüger et al. (2021) |
| Galuskina et al. (2024) | |
| Galuskina et al. (2026) | |
Jordan | |
| Khoury et al. (2015) +1 other reference |
Middle East | |
| Vapnik et al. (2014) | |
Mongolia | |
| Savina et al. (2020) |
Palestine | |
| Galuskina et al. (2024) |
Russia | |
| Cesnokov et al. (1998) |
| Shchipalkina et al. (2016) |
| Zhitova et al. (2025) |
USA (TL) | |
| Cosca et al. (1988) |
| Cosca et al. (1988) |
Quick NavTopAbout DorriteUnique IdentifiersSimilar NamesIMA Classification Classification Mineral SymbolsPhysical Properties Optical Data Chemistry Crystallography X-Ray Powder DiffractionGeological EnvironmentType Occurrence SynonymsOther LanguagesRelationshipsCommon AssociatesStrunz-MindatOther InformationInternet Links References Localities Locality List
Caspar quarry, Ettringen, Vordereifel, Mayen-Koblenz, Rhineland-Palatinate, Germany