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Biotite from
Nchisi Island (Chilwa Island; Shirwa Island), Zomba, Southern Region, Malawi

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Predictive Mineralogy

Locality type:

Island

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:

136 ± 7 Ma

Minimum recorded age:

136 ± 7 Ma

Sample ages:

	Recorded age	Geologic Time	Sample	Dating method
1	136 ± 7 Ma	Early/Lower Cretaceous	-	K-Ar

Sample references:

1	-	*SNELLING, N. J. (1965) Age Determinations on Three African Carbonatites. Nature, 205 (4970). 491 doi:10.1038/205491a0*

Confirmation

Validity:

Believed Valid

Data

Mineral Data:

Click here to view Biotite data

Locality Data:

Click here to view Nchisi Island (Chilwa Island; Shirwa Island), Zomba, Southern Region, Malawi

Data Identifiers

Mindat Occurrence Record ID:

715034

Long-form Identifier:

1:3:715034:0

GUID (UUID V4):

0

Nearest other occurrences of Biotite

11.9km (7.4 miles)

ⓘ Mpyupyu Hill, Zomba, Southern Region, Malawi

32.2km (20.0 miles)

ⓘ Mongolowe-Chaone-Chikala Complexes, Machinga, Southern Region, Malawi

32.9km (20.5 miles)

ⓘ Mount Malosa, Zomba, Southern Region, Malawi

33.8km (21.0 miles)

ⓘ Nkalonje Hills, Phalombe, Southern Region, Malawi

43.1km (26.8 miles)

ⓘ Machemba Mountain, Phalombe, Southern Region, Malawi

45.2km (28.1 miles)

ⓘ Chinduzi Intrusion, Mongolowe-Chaone-Chikala Complexes, Machinga, Southern Region, Malawi

47.4km (29.4 miles)

ⓘ Songwe Hill REE Project (Songwe Hill carbonatite), Phalombe, Southern Region, Malawi

47.6km (29.6 miles)

ⓘ Junguni Hill, Machinga, Southern Region, Malawi

53.1km (33.0 miles)

ⓘ Michese Intrusion, Phalombe, Southern Region, Malawi

68.8km (42.8 miles)

ⓘ Mulanje Massif (Mlange Massif), Mulanje, Southern Region, Malawi

References

Garson, M. S., & Smith, C. W. (1958). Chilwa Island: Geol. Surv. Nyasald., Mem, 1.

SNELLING, N. J. (1965) Age Determinations on Three African Carbonatites. Nature, 205 (4970). 491 doi:10.1038/205491a0

Woolley, A. R. (1969). Some aspects of fenitization with particular reference to Chilwa Island and Kangankunde, Malawi. British Museum (Natural History), Mineralogy, 2, 189-219.

Woolley, A. R.; Jones, G. C. (1987) The petrochemistry of the northern part of the Chilwa alkaline province, Malawi, in Alkaline Igneous Rocks. Geological Society, London, Special Publications, 30 (1). 335-355 doi:10.1144/gsl.sp.1987.030.01.16

SIMONETTI, A., BELL, K. (1994) Isotopic and Geochemical Investigation of the Chilwa Island Carbonatite Complex, Malawi: Evidence for a Depleted Mantle Source Region, Liquid Immiscibility, and Open-System Behaviour. Journal of Petrology, 35 (6) 1597-1621 doi:10.1093/petrology/35.6.1597

Eby, G.N., Roden-Tice, M., Krueger, H.L., Ewing, W., Faxon, E.H., Woolley, A.R. (1995) Geochronology and cooling history of the northern part of the Chilwa Alkaline Province, Malawi. Journal of African Earth Sciences, 20 (3) 275-288 doi:10.1016/0899-5362(95)00054-w

Berger, Vladimir I.; Singer, Donald A.; Orris, Greta J. (2009) Carbonatites of the World, Explored Deposits of Nb and REE—Database and Grade and Tonnage Models . Open-File Report 2009-1139. US Geological Survey doi:10.3133/ofr20091139

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