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Chromatite

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Formula:
CaCr6+O4
Colour:
Yellow, violet
Lustre:
Dull, Earthy
Specific Gravity:
3.142 (Calculated)
Crystal System:
Tetragonal
Name:
Named by F. J. Eckhardt and W. Heimbach in 1963 for the chemical composition.
Earthy yellow coatings.
Isotypic with zircon and xenotime.

Compare 'UM2011-01-CrO:CaH' - a dihydrate counterpart; and the compositionally similar 'Unnamed (Calcium Chromium Oxide Postspinel)'.


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Classification of ChromatiteHide

Approved
7.FA.10

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
A : Without additional anions
Dana 7th ed.:
35.3.2.1
35.3.2.1

35 : ANHYDROUS CHROMATES
3 : AXO4
27.2.3

27 : Sulphites, Chromates, Molybdates and Tungstates
2 : Chromates

Pronounciation of ChromatiteHide

Pronounciation:
PlayRecorded byCountry
Jolyon & Katya RalphUnited Kingdom

Physical Properties of ChromatiteHide

Dull, Earthy
Transparency:
Translucent
Comment:
Low luster reported because of the powdery occurrence
Colour:
Yellow, violet
Comment:
Violet crystals (Mo-, Pb-bearing) from Bleiberg, Austria.
Streak:
Yellow
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
3.142 g/cm3 (Calculated)

Optical Data of ChromatiteHide

Type:
Uniaxial (+)
RI values:
nω = 1.810 - 1.850 nε = 1.840 - 1.880
Max Birefringence:
δ = 0.030
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Very High

Chemical Properties of ChromatiteHide

Formula:
CaCr6+O4

Crystallography of ChromatiteHide

Crystal System:
Tetragonal
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
I41/amd
Cell Parameters:
a = 7.242 Å, c = 6.290 Å
Ratio:
a:c = 1 : 0.869
Unit Cell V:
329.89 ų (Calculated from Unit Cell)
Morphology:
Observed as earthy coating at type locality

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.62 (100)
2.88 (20)
2.68 (50)
2.56 (10)
2.38 (20)
1.85 (40)
1.81 (20)
1.50 (10)
Comments:
8-458 synthetic

Type Occurrence of ChromatiteHide

General Appearance of Type Material:
Earthy coatings
Geological Setting of Type Material:
In sedimentary rock units at the type location.
Associated Minerals at Type Locality:

Other Language Names for ChromatiteHide

German:Chromatit
Spanish:Cromatita

Related Minerals - Nickel-Strunz GroupingHide

7.FA.05TarapacáiteK2(CrO4)Orth. mmm (2/m 2/m 2/m)
7.FA.15HashemiteBa(CrO4)Orth. mmm (2/m 2/m 2/m) : Pnma
7.FA.20CrocoitePb(CrO4)Mon. 2/m : P21/b

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

27.2.1TarapacáiteK2(CrO4)Orth. mmm (2/m 2/m 2/m)
27.2.2LópeziteK2Cr2O7Tric. 1 : P1
27.2.4HashemiteBa(CrO4)Orth. mmm (2/m 2/m 2/m) : Pnma
27.2.5CrocoitePb(CrO4)Mon. 2/m : P21/b
27.2.6PhoenicochroitePb2(CrO4)OMon.
27.2.7SantanaitePb11(CrO4)O12Hex. 6 2 2 : P63 2 2
27.2.8IranitePb10Cu(CrO4)6(SiO4)2(OH)2Tric.
27.2.9HemihedritePb10Zn(CrO4)6(SiO4)2(OH)2Tric.

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.

References for ChromatiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Clouse, J.H. (1932): Investigations on the X-ray crystal structures of CaCrO4, CaCrO4⋅H2O and CaCrO4⋅2H20. Z. Kristallogr. A83, 161–171.
Zeitschrift für Kristallographie: 83: 1612-171.
American Mineralogist: 49: 438.
Eckhardt, E.J. and Heimbach, W. (1963): Ein natürliches Vorkommen von CaCrO4 (Chromatit). Naturwissenschaften, 50, 612.
Heimbach, W. (1965): Zum Vorkommen von Chromatit, CaCrO4, in Jordanien. Geologisches Jahrbuch, 83, 717–724 (in German).
Weber, G., Range, K.-J. (1996): Die Kristallstruktur von Calciumchromat(VI), CaCrO4. Zeitschrift für Naturforschung, B: Chemical Sciences, 51, 751-753.

Internet Links for ChromatiteHide

Localities for ChromatiteHide

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 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Austria
 
  • Carinthia
    • Gailtaler Alpen & Karnische Alpen
      • Bleiberg District
        • Bad Bleiberg
Puttner, M. (1997): Chromatit-Kristalle auf Bleiberger Wulfenit - ein natürliches Vorkommen von CaCrO4. Carinthia II, 187./107., 61-65. [http://www.zobodat.at/pdf/CAR_187_107_0061-0065.pdf]
Israel
 
  • Negev
Gross, S. (1977): The Mineralogy of the Hatrurim Formation, Israel. Geological Survey of Israel, Bulletin no. 70, 80 pp.
Shulamit Gross (1977) The mineralogy of the Hatrurim Formation, Israel. Geol. Surv. of Israel, Bull. # 70.
Norway
 
  • Telemark
    • Porsgrunn
      • Bjørkedalen
Piilonen, P.C., McDonald, A.M., Poirier, G., Rowe, R. & Larsen, A.O. (2012): The mineralogy and crystal chemistry of alkaline pegmatites in the Larvik Plutonic Complex, Oslo rift valley, Norway. Part 1. Magmatic and secondary zircon: implications for petrogenesis from trace-element geochemistry. Mineralogical Magazine. 76, 649-672; Larsen, A. O. (2013): Contributions to the mineralogy of the syenite pegmatites in the Larvik Plutonic complex. Norsk Bergverksmuseum Skrifter. 50, 101-109
Palestine (TL)
 
  • West Bank
    • Hatrurim formation
Naturwiss.(1963) 50, 612; Sokol, E.V., Gaskova, O.L., Kokh, S.N., Kozmenko, O.A., Seryotkin, Y.V., Vapnik, Y., Murashko, M.N. (2011): Chromatite and its Cr3+- and Cr6+-bearing precursor minerals from the Nabi Musa Mottled Zone complex, Judean Desert. American Mineralogist 96, 659-674.
Sokol, E.V., Gaskova, O.L., Kokh, S.N., Kozmenko, O.A., Seryotkin, Y.V., Vapnik, Y., Murashko, M.N. (2011): Chromatite and its Cr3+- and Cr6+-bearing precursor minerals from the Nabi Musa Mottled Zone complex, Judean Desert. American Mineralogist 96, 659-674.
South Africa
 
  • Limpopo Province
    • Bushveld Complex
http://www.fc.up.pt/geo/ecrofi/377.PDF; McDonald, I., Vaughan, D. J., & Tredoux, M. (1995). Platinum mineralization in quartz veins near Naboomspruit, central Transvaal. S. Afr. J. Geol, 98, 168-175.
Mineral and/or Locality  
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