Map India 2005 Geomatics 2005

Map India 2005 Geomatics 2005 

Exploitation of Corundum at Lakshmipuram, Khammam District 

Andhra Pradesh, India. 

Narayan Sangam & Pavanaguru, R. 

Dept. of Geology, Osmania University, Hyderabad-500 007 

Narayan_sangam@rediffmail.com,pavanaguru@rediffmail.com 

Keywords: Lakshmipuram, Khammam Schist Belt, Mineral Resource, Corundum 

Exploitation ,Mineralisation, Remote-sensing studies&GIS 

Abstract 

Mineral corundum, an oxide of alumina of semi-precious nature is occurring in the 

vicinity of Lakshmipuram area, Khammam District, Andhra Pradesh.Corundum, in 

particular, apart from other minerals, is being extensively exploited by the local people 

without having any proper knowledge of its parent/source rock. 

In the past as well as the present day, the local people have employed the pits 

and trenching method of corundum exploitation wherein, the mineral corundum is being 

transported from the upper reaches (Hills of Gobbagurti) and gets concentrated in these 

pits and trenches, mostly along the nalah cuttings and lower reaches of the stream 

network. Crystals of Corundum are being collected soon after the rains by means of 

panning the soil cover. 

The present research paper is an attempt towards understanding the 

Petrogenesis of Corundum and its controls of Mineralisation using the Techniques of 

Remote sensing and GIS. 

Introduction: 

Khammam district, of Andhra Pradesh is known for its occurrences of precious 

and semi-precious mineral resources in commercial quantities(Corundum&Garnet) 

Corundum in the form of ruby, light pink or red, and ordinary corundum variety is 

occurring in Lakshmipuram area, which is included in the Konijerla mandal of Khammam 

district. The area is located about 12 kms. east of Khammam town and is quite 

accessible . 

© Map India 2005

The haphazard exploitation activity of corundum by the local entrepreneurs along 

certain faiths and beliefs, is going on in this area over a considerable period of time. The 

state authorities have investigated these areas where exploitation has been done and 

reported in their annual technical reports (DMG 2001-2002). Some of the previous 

contributions from the geologists who have studied this area, which is a part of 

Khammam Schist Belt, on the geology and petrogenetic evolution as it occupies pivotal 

position among the various litho units of the schist belts in the eastern Dharwar craton 

include (Balakrishna & Subbaraju (1976), Sarvothaman H. (2001), Leelanandam & 

Narsimha reddy (1985), Ramakrishnan.M etal (1998), Ramam&Murthy (1997). The 

geology of corundum occurrences have been a subject of considerable economic 

importance and many workers in recent times have contributed on this subject 

(Chandrasekhar, H and Nazeer Ahmed (1994), Devaraju, T.K. and Alikhan, M.A., (1981), 

Gandhi Prasad et.al. (1984), Panjikar et.al (1985), Rama Rao B. (1962), Ravindra 

et.al.(1990) Viswanatha M.N. (1972), Dayasankar et al.(2001) Narayan Sangam(2002) 

Narayan Sangam & Pavanaguru(2002). Narayan Sangam(2004) 

The area of investigation poses several complexities with respect to its geology, 

structure and tectonics in view of the nature and controls of corundum mineralisation. As 

no comprehensive work on with regards to its petrogenesis and mineralisation has been 

done in the past, systematic investigations were attempted using the techniques of 

Remote sensing and GIS. Integrated remote sensing methods, incorporating distinct 

themes have been emphasized to facilitate the identification of zones of mineralisation of 

corundum in this area. 

Data Used: 

Remote sensing studies using IRS 1C/1D LISS III Geocoded FCC image dated 

Feb. 99 has been utilized and interpreted and different overlays of information 

concerning geology, structure, geomorphology, drainage has been synthesized to arrive 

at a meaningful solutions. SOI Toposheets(65c/7&65c/8) and Geological map(GSI) were 

also utilized for this study. 

Geology of the area 

The Lakshmipuram area is a part of the Khammam schist belt. It is situated along 

the northern continuity of the Nellore schist belt, south of river Godavari. The Geological 

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formations of the area is comprised of Amphibolites, Biote-granite gneisses, Schists of 

various types, which are intruded at places by the quartzo-felspathic mobilisates in the 

form of Pegmatites. These rock types are sporadically exposed as most of the area is 

covered by soil cover. The Nagarjunasagar Left Canal excavations through this area 

exposed many salient geological features of great importance. 

Stratigraphic succession of the area 

Era 

Recent 

Precambrian 

Lithology 

Soil cover with colluvium and alluvium 

Quart veins 

Pegmatites 

Aplites 

Quartzofespathic rock (Granite) 

Charnockite 

Metadolerite 

Schists—Sillimanite-Quartz-Chlorite-Hornblende-Biotite, 

Garnetiferous schists 

Amphibolite 

Peninsular Granite-gneissic complex 

Structure: 

NW-SE trending cratonic fold occupying a major fracture developed internal to 

the axis of the Chimalpahad Anorthosite Gabbro Complex (CAGC) The general strike of 

the foliations in the schists of various types varies from N 30 0 W to S 30 0 E to N 50 0 W 

to S 50 0 E with varying dips towards east. Predominant shear joints parallel to major 

shear zones (interpreted from satellite imagery) along N 10 0 W and N-S are observed 

where outcrops are exposed and exhibit with almost vertical dips. The foliation trends 

and the shear planes can be correlated with the well preserved transpressional shears 

observed in the), described by Leelanandam et al.(2002). With the available satellite and 

field data of joint patterns and foliation trends a structural map of the area has been 

prepared (Fig 3). Felsic rocks such as Granite, Aplites and pegmatite. Number of quartz 

veins has emplaced the planes of schistosity in amphibolites and the associated shear 

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fractures. Three sets of joints are common: N 45 0 E to S 45 0 W/70 deg vertical, N 10 0 W 

to S 10 0 E /vertical and N 45 0 W to S 45 0 E/vertical 

Mode of occurrence of Corundum 

The mode of occurrence of Corundum (all varieties) in Gubbagurti area is in the 

form of float, insitu and placers. Float deposits are observed in close proximity to the 

primary occurrence and is mixed with soil cover or weathered zones of the rock or in the 

colluvium mixed with quartz and it is very difficult to observe unless the eyes are properly 

trained. 

Insitu occurrence of corundum is noticed in association with felspathic rocks and 

pegmatite emplaced into the structural planes of amphibolites. The contact between 

felspathic rock and the garnetiferous amphibolites forms major insitu occurrence. The 

dug material shows the presence of weathered pegmatite associated with amphibolite. 

Petrographically corundum with lamellar twinning is associated with coarse grain 

felspathic rock. 

Placer concentrations are exploited along the Nalla courses. Expansive panning 

of alluvium is observed and the recoveries are also encouraging particularly during rainy 

season. It is vividly observed along the culverts where prospecting pits by the locals 

amply justify the transportation of corundum from the upper reaches of the stream 

system. The significant feature of corundum occurrence is along the structural trends, 

which control the drainage pattern, and where colluvium is extensively associated with 

pebbles of quartz. Placer accumulations with thickness of about 10 Cm. lying below a 

thick soil cover of about 1m. spread over a large aerial extent is under active 

exploitation. 

Exploitation and Extraction of Corundum: 

Corundum pieces are collected soon after the rains generally at the periphery of 

the basic rocks as pyroxene granulites, amphibolites and schists. The detrital corundum 

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occurs as ill defined crystals of 0.25 to 0.5*1.0 cm in size but well developed prismatic 

crystals as big as 2cm*4cm are not uncommon. Corundum is invariably present where 

the soil is underlain by brownish granule zone consisting of very small fragments of 

sillimanite, ferruginous matter and quartz in a matrix of brown soil. The thickness varies 

from 0.15 to 0.30m. 

Lakshmipuram Area: 

The incidence of corundum is spread over 50 hectares of the area which 

is under cultivation. Old pits and dumps south of Lakshmipuram village comprise 

decomposed basic rocks, white mica and acicular sillimanite. Trenches expose biotite 

gneisses, amphibolites, quartz-sillimanite gneisses and mica schists wherein light pink 

,translucent variety is found to occur. One trench exposed sillimanite schists, sillimanite 

corundum, bounded by biotite gneisses. Corundum is reported to occur in association 

with the sillimanite bearing schists which are intruded at places by quartzo felspathic 

pegmatites. 

The sillimanite horizon starts at 2.20m and continues upto 4.90m in depth.Here, 

translucent to semitransparent variety of light to dark purple coloured corundum is found 

to occur.(0.5 to 1cm) in size.Insitu corundum is reported to occur at 1.50m depth. 

Geomorphology: 

The area possesses dendritic to sub-dendritic drainage. Majority of the 

streams drain into NW-SE and N-S trending major streams and enter into the pediment 

area and finally discharge into Wyra lake. They lose their velocity as they approach the 

lower reaches and thus helps in continuous deposition of their content in the meanders 

and confluence points of different nallas. They carry along with them rich colluvial 

corundum and all the culverts are the focal points for placer accumulations which are 

actively exploited in this area. The geomorphic units comprise of Denudational hills, 

Residual hills, Structural hills, Pediment zones, Pediplain shallows and Valley fills. 

Discussion and conclusions 

Corundum occurrences in and around Gobbagurti area consist of Singaraipalem, 

Ratnapuram, Lakshmipuram, Nallagutta and Tummalepalle villages of Konijerla mandal. 

If the entire cratonic zone is studied in detail, major amounts of Corundum, Ruby and 

Garnet minerals can be explored in million tonnes. Sillimanite and Sericite bearing 

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schists are occasionally observed in close proximity with the mineralisation. The 

petrographic studies of the host rocks clearly indicate the occurrence of corundum with 

quartzo felspathic rocks. However, corundum is not found with in amphibolitesCorundum 

is observed in colluvium particularly along the meander points of the drainage pattern in 

the Lakshmipuram area forms both float and placer concentrations. In addition to the 

micro level geological exploration, petrology, mineralogy and geochemistry can give rise 

to invaluable information on Corundum, Ruby and Garnet minerals. 

As there is no direct evidence as to the source rock for corundum in the area, it 

could be presumed that corundum could have formed due to the desilication of quartz 

and alumina rich rocks traversed by ultrabasic/ultramafic rocks. 

From the studies it is concluded that: 

1. Precious and semi precious variety corundum is significantly 

mineralised in Lakshmipuram area and also concealed under soil 

cover. 

2. Lithology, structure and geomorphology controls and concentrate 

mineralisation. 

3. Remote sensing studies facilitated to delineate the favourable 

extended zones of mineralisation. 

4. To explore full potential of mineralisation and the nature of 

intrusives and their metamorphic history it is imperative to initiate 

a detailed petrological and structural investigations 

5. A comprehensive geoscientific evaluation is a necessity to 

identify the richness of the deposits. 

Acknowledgements 

The authors thank Dr. V. Diwakar Rao and Dr. M.N. Reddy of geology Dept. 

Osmania University for their useful discussions during the preparation of this paper. The 

help and cooperation received from Dr. K. Paninder Rao of State Ground water 

department and Sri Narahari of Geological survey of India, Hyderabad is gratefully 

acknowledged. 

: 

References: 

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