Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite
Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
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Biotite from
Messum Igneous Complex, Brandberg Area, Dâures Constituency, Erongo Region, Namibia


Locality type:Complex
Classification
Species:'Biotite' (not an IMA approved species)
Formula:K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Age information
Maximum recorded age:149 ± 1 Ma
Minimum recorded age:149 ± 1 Ma
Sample ages:
Recorded ageGeologic TimeSampleDating method
1149 ± 1 MaLate Jurassic - Ar/Ar
Sample references:
1 -
Fitch, F. J., & Miller, J. A. (1984). Dating Karoo igneous rocks by the conventional K-Ar and 40Ar/39Ar age spectrum methods. In:Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publication, 13, 247-266.
Confirmation
Validity:Believed Valid
Data
Mineral Data:Click here to view Biotite data
Locality Data:Click here to view Messum Igneous Complex, Brandberg Area, Dâures Constituency, Erongo Region, Namibia
Data Identifiers
Mindat Occurrence Record ID:1432016
Long-form Identifier:1:3:1432016:9
GUID (UUID V4):0
Localities for Biotite in this Region
Messum Crater, Messum Igneous Complex, Brandberg Area, Dâures Constituency, Erongo Region, Namibia
References
Mathias, M. (1956): The petrology of the Messum igneous complex, South-West Africa. Transactions of the Geological Society of South Africa, 59, 1-35. doi.org/10.10520/AJA10120750_2142
Korn, H. & Martin, H. (1955): The Messum igneous complex in South-West Africa. Transactions Geological Society of South Africa, 57, 83-124.
Mathias, Morna (1957) The geochemistry of the Messum Igneous Complex, South-West Africa. Geochimica et Cosmochimica Acta, 12 (1) 29-46 doi:10.1016/0016-7037(57)90015-7
Allsopp, H. L., Bristow, J. W., Logan, C. T., Eales, H. V., & Erlank, A. J. (1984). Rb-Sr geochronology of three Karoo-related intrusive complexes. In: Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publications, 13, 281-287.
Fitch, F. J., & Miller, J. A. (1984). Dating Karoo igneous rocks by the conventional K-Ar and 40Ar/39Ar age spectrum methods. In:Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publication, 13, 247-266.
Allsopp, H. L., Bristow, J. W., Logan, C. T., Eales, H. V., & Erlank, A. J. (1984). Rb-Sr geochronology of three Karoo-related intrusive complexes. In: Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publications, 13, 281-287.
Fitch, F. J., & Miller, J. A. (1984). Dating Karoo igneous rocks by the conventional K-Ar and 40Ar/39Ar age spectrum methods. In:Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publication, 13, 247-266.
Allsopp, H. L., Bristow, J. W., Logan, C. T., Eales, H. V., & Erlank, A. J. (1984). Rb-Sr geochronology of three Karoo-related intrusive complexes. In: Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publications, 13, 281-287.
Fitch, F. J., & Miller, J. A. (1984). Dating Karoo igneous rocks by the conventional K-Ar and 40Ar/39Ar age spectrum methods. In:Erlank, A.J. (ed.) Petrogenesis of the volcanic rocks of the Karoo Province. Geological Society of South Africa, Special Publication, 13, 247-266.
Aldrich, S. (1986). Progress report on a gravity and magnetic investigation of the Messum and Erongo igneous complexes. Communications of the Geological Survey of South West Africa/Namibia, 2, 47-52.
Milner, S. C., & Ewart, A. (1989). The geology of the Goboboseb Mountain volcanics and their relationship to the Messum Complex, Namibia. Communications of the Geological Survey of Namibia, 5, 31-40.
Harris, Chris (1995) Oxygen isotope geochemistry of the Mesozoic anorogenic complexes of Damaraland, northwest Namibia: evidence for crustal contamination and its effect on silica saturation. Contributions to Mineralogy and Petrology, 122 (3) 308-321 doi:10.1007/s004100050130
MILNER, S. C., LE ROEX, A. P., O'CONNOR, J. M. (1995) Age of Mesozoic igneous rocks in northwestern Namibia, and their relationship to continental breakup. Journal of the Geological Society, 152 (1). 97-104 doi:10.1144/gsjgs.152.1.0097
Harris, Chris (1995) Oxygen isotope geochemistry of the Mesozoic anorogenic complexes of Damaraland, northwest Namibia: evidence for crustal contamination and its effect on silica saturation. Contributions to Mineralogy and Petrology, 122 (3) 308-321 doi:10.1007/s004100050130
MILNER, S. C., LE ROEX, A. P., O'CONNOR, J. M. (1995) Age of Mesozoic igneous rocks in northwestern Namibia, and their relationship to continental breakup. Journal of the Geological Society, 152 (1). 97-104 doi:10.1144/gsjgs.152.1.0097
Harris, Chris (1995) Oxygen isotope geochemistry of the Mesozoic anorogenic complexes of Damaraland, northwest Namibia: evidence for crustal contamination and its effect on silica saturation. Contributions to Mineralogy and Petrology, 122 (3) 308-321 doi:10.1007/s004100050130
MILNER, S. C., LE ROEX, A. P., O'CONNOR, J. M. (1995) Age of Mesozoic igneous rocks in northwestern Namibia, and their relationship to continental breakup. Journal of the Geological Society, 152 (1). 97-104 doi:10.1144/gsjgs.152.1.0097
 
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