 |
Mosaboni (Singhbhum Copper Belt)
Bihar, India
Main commodities:
Cu
|
 |
|
Deposit Description
The Mosaboni copper mine is located within the Singhbhum Copper Belt in Bihar State, northern India.
The Singhbhum Copper Belt is structurally controlled, comprising a series of tabular bodies distributed over a length of around 160 km within the Singhbhum Thrust/Shear zone, which is interpreted to be part of the Central Indian Suture zone. The most intense mineralisation however is in a 50 to 60 km interval in the central and south-central sections of the shear zone/over-thrust. This thrust/shear generally dips gently to the north at angles of between 30 and 50°, and is very persistent with depth, having been traced down dip as far as 2.7 km. The shear plane also acts as the loci of ultramafic and mafic igneous activity and of soda-metasomatism and apatite-magnetite-uranium-copper mineralisation within the district.
In the vicinity of the Mosaboni mine, garnetiferous mica schists, phyllites, quartzites and quartz-kyanite schists of the Chaibasa Formation (Singhbhum Group), have been thrust over metamorphosed mafic volcanics of the Dhanjori Formation to the south. Rocks within the shear zone are highly sheared and mylonitised equivalents of siliceous rocks, quartzites and granites, and are characterised by soda rich feldspars (Khan, 1976). The shear zone itself varies from a few hundred metres to 2.5 km in width and contains slices of sheared Dhanjori epi-diorite and quartzite, sometimes accompanied by kyanite-hornblende-mica schist and soda-feldspathised schist. At Mosaboni it dips on average at 30°NE, generally varying from 25 to 30°, although in places it gets up to 50°. Schistosity, strain slip cleavage and shear planes are developed throughout the thrust zone in the mine. The S2 foliation within the thrust zone is sub-parallel to the S3 shear planes.
Mineralisation at Mosaboni is found close to the footwall of the thrust belt in two sheet like lodes that each average around 1.8 m in thickness and are generally 12 m apart. These are known as the 'Main Lode' and the 'West Lode', representing the hangingwall and footwall lodes respectively. They parallel the structural planes of the shear and follow two well defined shear channels over an aggregate length of around 5 km, with barren/poorly mineralised intervals in the plane of the lode between the ore shoots. The width of the mineralised lode varies from a few cm's to 11 m within these lodes (Khan, 1976; Johnson, 1973). Known mineralisation extends down plunge for at least 2.6 km (Sarkar, etal., 1971).
These lodes are confined to a zone of quartz-biotite-chlorite schist within the 'soda granite' and is regarded to post date the soda-metasomatism. The West Lode occurs about 50 m above the contact between the 'soda granite' with the underlying, 40 m thick sheared and feldspathised Dhanjori epidiorite, the base of which defines the lower limit of the shear (Johnson, 1973).
The lodes consist of sheeted orebodies formed by sulphides infilling close spaced inter-locking fractures and by occasional massive sulphide pods and bands. These fractures and bands are defined by the S2 and S3 foliations. The orebodies at Mosaboni generally have sharp boundaries, although elsewhere they may also have assay limits. Some blebs of disseminated sulphides and small stringers may occur between the two lodes. Individual orebodies/shoots within the lodes vary in strike length from a few tens of metres to >1000 m, but are generally more extensive down-plunge (Temby, 1978; Johnson, 1973).
The sulphide minerals consist predominantly of chalcopyrite, followed by pyrite and pyrrhotite, accompanied by magnetite and minor pentlandite, millerite, violarite, sphalerite and molybdenite. The gangue minerals are quartz, biotite, chlorite and sericite in variable proportions (Sakar, etal., 1971). Magnetite and apatite are also occasionally gangue minerals. Quartz veins are not always mineralised. The sulphides are enriched in Co, Ni, Ti and V, as are the rocks of the Singhbhum Shear Zone, a relationship that has been quoted to support the derivation of metals from the rocks of the shear zone.
Reserves indicated in 1978 amounted to: 29 Mt @ 1.6% Cu, while in 1994 another author quoted 17 Mt @ 1.73% Cu.
For details consult the reference(s) listed below.
Description based on information available at, or was up to date when written in 1996.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
|
|
| References to this deposit in the PGC Literature Service Collection: |  |
 |
 |
|
Banerji A K 1981 - Ore genesis and its relationship to volcanism, tectonism, granitic activity and metasomatism along the Singhbhum shear zone, eastern India: in Econ. Geol. v76 pp 905-912
|
Changkakoti A, Gray J, Morton R D, Sarkar S N 1987 - The Mosaboni Copper deposit, India - a preliminary study on the nature and genesis of the ore fluids: in Econ. Geol. v82 pp 1619-1625
|
Search Again | PGC Home | Terms & Conditions
|
|
