Summary:
The deposit forms part of the pre-Aravalli Gneissic Complex. This consists of gneisses, schists and intrusive acidic and basic igneous rocks that occupy predominantly the south-eastern plains of Ajmer and Bhilwara. The rock units show NE-SW strike with steep dips in the hanging wall (750-800) and moderate dips in the footwall (600-650) towards the south-east and plunges NNE. The sequence of rocks, from hanging wall to footwall, can be broadly grouped as:
• Garnet-biotite-sillimanite gneiss with intermittent bands of calc-granulites, amphibolites and aplites or pegmatites.
• Garnet-mica-sillimanite gneiss/schist.
• Garnet-biotite-sillimanite gneiss with lenses of quartzo-feldspathic bands, amphibolites, pegmatites and aplites.
• Granite gneiss
• Mylonitic rocks.
Economic mineralization is predominantly in graphite-mica-sillimanite schist over the strike length of 1,550m. The ore zone has a sharp contact with the hanging wall and footwall. The hanging wall side of the lode is the richest and widest, followed by comparatively lean grade in the middle and a narrow, rich, footwall zone. Coarse grained crystalline galena, associated with pyrite and pyrrhotite is noted in the hanging wall rocks. The mineralization in the hanging wall and footwall contacts is invariably fine to coarse grained and is made up of sphalerite and galena with numerous inclusions or rounded to sub-rounded discrete grains of feldspar, quartz, hornblende, sillimanite and dark green chlorite.
The general strike of the ore zone is parallel to the enclosing rocks, which is roughly NE-SW. The dip of the ore zone varies along the strike and depth. Near the surface, the dip of the hanging wall is steeper (750 -800 SE) as compared to footwall contact (about 600 SE). In deeper levels, both the hanging wall and footwall contacts show a tendency to flatten. In general, the dip varies from 500 to 800 .The ore zone show a variation in width, both along strike and dip. The width of the ore zone gradually widens to about 95m to 100m between -200m north and -400m north.
The main ore mineralisation is predominantly contained within two lenses, namely the Main Lens and K1 Lens. Both the Main and K1 Lenses trend NNE-SSW to NE-SW, parallel to the dominant structural trend defined by the open synformal fold. The Main Lens strikes over 900 m and extends to a depth of approximately 375 m. The body is characterised by a strong pinch and swell geometry, ranging in width from 5-40 m, and is regularly intruded by barren pegmatite dykes. The K1 Lens is a steeply (75- 80°) SE dipping body, striking NE-SW over a strike length of approximately 250 m. The K1 Lens has an average width of 4 m and extends to a maximum depth of 110 m.
Deposit Types
There are four major lenses – the Main lens, K1 lens, S1 lens & K18 lens and two minor lenses in resources category namely S2 lens & NEML lens. The main host rock is quartz mica schist with some mineralization in calc silicate. The Main Lens has been dissected in many places by pegmatite. The lenses lie parallel to the axial plane foliation/ cleavage/ fracture of the fold system or shear fractures governed by the lithological variations. The main lens has been explored to variable depths and maximum up to 50 mRL.
The main lens ranges in average width from 5 m in steeper portions to about 35m in the flat lying portion. Maximum strike of the main lens is 900 m at the depth of approximately 250 m from the surface. It shows a general reducing trend in depth. This lens shows swelling and pinching nature probably because of superimposition of different phases of folding.
K1 lens has strike of 250 m and the average width of 4 m. This is comparatively a richer lens as far as the metal content is concerned. The exploration during December 2011 has delineated a minor lens (S1 lens) on the southern side of the main lens which has strike of 150m and the average width of 3m
Mineralization
The mineralization occurs predominantly in quartz mica schist along with calc silicate rock. The massive Zn-Pb mineralization is hosted by QMS in contact with Calc-silicate. The Calc-silicate and quartzite occurring to West, towards foot wall side carry minor disseminations and stringers.
Lead zinc mineralization occurs mainly at the interface of QMS and Calc Silicate with the earlier rock seeming to be the main host rock. The main host rock is QMS with some mineralization also occurring in calc silicate. The main ore minerals are sphalerite and galena. Chalcopyrite occurs in minor proportions mostly on footwall of the ore body. Other sulphides like pyrrhotite and some pyrite also constitutes the assemblage. The sulphides occur as discontinuous veins, massive bands, fracture fillings, and occasionally as disseminations. Sphalerite is coarse to medium grained. Galena occurs as medium grained inclusions, patches and small stringers within sphalerite and pyrrhotite. Chalcopyrite is observed as fracture fillings within pyrrhotite and occasionally in sphalerite. Quartz, biotite, muscovite, feldspar with occasional amphiboles (hornblende) and garnet are the main gangue minerals.
The main ore minerals are sphalerite and galena. Chalcopyrite occurs in minor proportions mostly on footwall of the orebody. Other sulphides like pyrrhotite and some pyrite also occur. The sulphides occur as discontinuous veins, massive bands, fracture fillings, and occasionally as disseminations. Sphalerite is coarse to medium grained. Galena occurs as medium grained inclusions, patches, and small stringers within sphalerite and pyrrhotite. Chalcopyrite is observed as fracture fillings within pyrrhotite and occasionally in sphalerite. Quartz, biotite, muscovite, feldspar with occasional Amphiboles (hornblende) and garnet are main gangue minerals.