Sylvania Platinum Ltd. holds an indirect 74% interest via its subsidiary companies in the Volspruit Mining Company, with the remaining 26% held by Iolite Trading 16 (Pty) Ltd, the Black Economic Empowerment (BEE) participants.
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Summary:
The Volspruit Project is located within the southern portion of the Northern Limb just south of Mokopane and was described by Hulbert in 1983 (Hulbert, 1983).
The Volspruit Reef has provisionally been classified as a disseminated, PGE-Cu-Ni, syngenetic, orthomagmatic deposit within the Lower Zone of the RLS by Hulbert (1983).
The Volspruit Reef mineralisation is predominantly interstitial disseminated to net-textured sulphide assemblages hosted within olivine and chrome-bearing pyroxenites. The sulphide mineralisation within this horizon, in decreasing abundance, consists of pyrrhotite, pentlandite, chalcopyrite and cubanite (Hulbert, 1983). Sulphide assemblages reach their peak modal abundance at approximately 3 wt.% of the whole rock composition. Mineralisation is predominantly hosted by fine-grained equigranular ortho-pyroxenites with minor olivine and chrome occurrences.
The region, which is dominated by horst and graben structures, has undergone at least four deformational events, summarised below:
• An initial episode of north-south trending reverse faulting (age unknown). This event resulted in a Lower Zone block being displaced by approximately 800 m upwards through a set of imbricate faults into the Critical Zone. This fault system was later intruded by a granitic dyke swarm which may represent the formation of the Lebowa Granite Suite;
• The exposure of the Lower Zone Blocks within the Zoetveld, Volspruit and Vaalkop farms through WNW-ESE reverse faulting. This event resulted in a step-like displacement of the RLS towards the west. The age of this event is unknown;
• NE-SW striking faults resulting in slices of the Pretoria Group quartzites being thrust into the RLS. The age of these faults is believed to be post-Waterberg; and
• The final faulting event is estimated to have occurred post-Karoo resulting in Karoo basalts being brought into contact with the Lower Zone lithologies along the TML.
Locally, the stratigraphy of the Lower Zone has been sub-divided into three main groups, the Volspruit Pyroxenite, the Drummondlea Harzburgite Chromitite, and the Moordrift Harzburgite Pyroxenite, from the base upwards, with PGE-Cu-Ni mineralisation being hosted by the Volspruit Pyroxenite. This mineralised pyroxenite is observed in two separate bodies within the project area, the North and South bodies, which are separated by the Magoga Fault.
The Lower Zone stratigraphy comprises approximately 37 cyclic units, numbered from the base upwards. The Volspruit Reef (VR) sits within the upper portion of Cyclic unit 11, consisting predominantly of orthopyroxenite and varying proportions of olivine, chrome and minor plagioclase. Although sulphide mineralisation occurs within the units surrounding the Volspruit Reef, no grade has been reported for these units.
The sub-units VR1, VR2 and VR3 were observed as being the most consistently developed mineralised units and subsequently utilised to redefine the Mineral Resource.
Mineralisation observed within the units is typically disseminated to net-textured with no marker lithological units being present to assist in defining reef contacts. Sulphide minerals present, in order of abundance, are pyrrhotite, pentlandite, chalcopyrite and cubanite.