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GEOREF RECORD

Characterization of fibrous cryptomelane from the todorokite-cryptomelane mineral assemblage at the Sebilo Mine, northern Cape Province, South Africa

Nicholas Andrew Vafeas, K. S. Viljoen and Lauren Cher Blignaut
Characterization of fibrous cryptomelane from the todorokite-cryptomelane mineral assemblage at the Sebilo Mine, northern Cape Province, South Africa
The Canadian Mineralogist (January 2018) 56 (1): 65-76

Abstract

A 30-cm hand sample was obtained from the lowermost manganese ore bed, directly below the Kalahari unconformity within the supergene zone, at the Sebilo manganese mine in the Kalahari Manganese Field, Northern Cape Province, South Africa. The sample comprises an intergrowth of rare supergene fibrous cryptomelane and todorokite, as well as traces of pre-supergene manganese oxides. A chemical analysis of hausmannite concretions within remnant diagenetic manganese ore fragments in the supergene mineral assemblage shows leaching of pre-existing carbonate and silicate compounds from the primary diagenetic ore (Kleyenstuber 1984, 1985, Chetty 2008, Vafeas 2016) via descending meteoric fluids along the Kalahari unconformity. This resulted in the initial development of todorokite, forming the bulk of the matrix, and the coeval development of early-stage calcite within the todorokite pores. Subsequent to this, late-stage calcite precipitated from descending Ca-bearing supergene fluids and is seen to superimpose the todorokite matrix. Growth of the supergene mineral assemblage ended with the formation of rare medium- and coarse-grained acicular cryptomelane crystals that are orientated perpendicular to the host fracture surface.


ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 56
Serial Issue: 1
Title: Characterization of fibrous cryptomelane from the todorokite-cryptomelane mineral assemblage at the Sebilo Mine, northern Cape Province, South Africa
Affiliation: University of Johannesburg, Department of Geology, Johannesburg, South Africa
Pages: 65-76
Published: 201801
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 27
Accession Number: 2018-033711
Categories: Mineralogy of non-silicatesEconomic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch map
S28°00'00" - S27°00'00", E23°00'00" - E24°00'00"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201808
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