The mines at Banaganapalli (kurnool), the village that gives its name to the group of strata containing the diamantiferous sandstone, lie to the northwest of Condapetta and to the southwest of Nandial. According to the observations of Dr. W. King, the sandstones together with the diamond-bearing bed rest unconformably upon the older sedimentary rocks beneath - that is, the lines of bedding of the two series differ in inclination. These older sedimentary beds comprise shales and limestones with interbedded trap-rocks. The diamond-bearing bed and its associated sandstones are from 20 to 30 feet thick. They are penetrated on the hill slopes by pits never exceeding fifteen feet in depth, at the bottom of which the diamond-bearing bed has been removed as far in all directions as the stability of the overlying rock will permit. This bed, which is only from six to eight inches in thickness, is constituted of a coarse sandy or clayey conglomerate or breccia, consisting largely of variously colored fragments of shales and hornstone. Large diamonds have apparently never been found here. The crystalline forms of most common occurrence are those of the octahedron and the rhombic dodecahedron. Workers of the present day confine themselves for the most part to turning over the refuse-heaps of abandoned mines in search of small stones.
" The mines of Ramallkota are situated to the northwest of Banaganapalli and about nineteen miles south south west of Kurnool. They are in the Banaganapalli sandstone and are worked more deeply and extensively than are those of Chennur, near Cuddapah in the Penner valley. The stones found here are small and not very regular in form; they may be white (colorless), gray, yellow or green in color. The exact output is not known. The mines in the sandstone are not now worked, but the washing of the neighboring diamond-bearing sands is carried on to a small extent. Captain Newbold, who visited this district in 1840, saw only twenty men at work here, but in the dry season the number was said to be increased to 500. The rich and famous mines mentioned by Tavernier under the name Raolconda are probably identical with the mines of Ramallakota(kurnool); at the time of his visit (1665) these mines had been worked for 200 years and were a source of much wealth. After the working of these mines had ceased, their very situation became completely forgotten; they were at one time supposed to lie five days' journey west of Golconda, near the junction of the Bhima and Kistna rivers, and eight or nine days' journey from Visapur (now Bijapur); the researches of V. Ball have now, however, practically established the identity of these mines with the Ramallakota mines of the present day.
The Golconda Group on the Krishna River
<span style=" The mines of this group are situated on the lower portion of the Krishna River and include some of the oldest and most famous of Indian diamond mines, the largest and most beautiful of Indian stones having been derived from these so-called Golconda mines. They derive their name, not from their situation, but from the fact that the diamonds from these mines were sent to the market held near the old fortress of Golconda, not far from Haidarabad, this being also the market for stones from Chennur. At the time of Tavernier's visit to these mines, more than twenty were being worked, most of them being extraordinarily rich. With two or three exceptions, the whole were later deserted, and the situations of many of them, including some, which Tavernier described as being most famous, are now forgotten. </span>
<span style=" The richest of the mines to the east of Golconda were those of Kollur, which lies on the right bank of the Krishna, west of Chintapilly and in latitude 16º 42-1/2' N. and longitude 80º 5' E. of Greenwich. This place was referred to by Tavernier under the name Gani Coulour, and now sometimes figures as Gani. This latter is a native word said to signify "mine", while the word Coulour, from which is derived the now common place-name Kollur, is of Persian origin. These mines are not identical, as has often been supposed, with the also far-famed mines of Partial; the latter, which will be described below, are situated somewhat further east and on the left bank of the Kistna. </span>
<span style=" The discovery of the diamantiferous deposit at Kollur was made about 100 years before Tavernier's visit, namely, about 1560. A 25-carat stone was first accidentally found, and numerous others soon followed, many weighing from 10 to 40 carats, and some still more. The quality of the stones, however, was not always as satisfactory as their size, cloudy and impure specimens being frequent. Such famous diamonds as the "Koh-i-noor," now in the English crown jewels, and the "Great Mogul," the whereabouts of which, unless it is identical with the " Koh-i-noor," is now unknown, were very probably found in these mines, in addition to some beautiful blue stones, including the Hope blue diamond. </span>
<span style=" Tavernier stated that 60,000 people were engaged in these mines at the time of his visit; today, however, they are completely deserted, as are also numerous other workings situated in the valley of the Kistna, between Kollur and Chintapilly, and between the latter place and Partial. The diamonds here lie in a loose alluvium, which is thus a diamond-sand. </span>
<span style=" In following the course of the Kistna river, a little beyond where it is joined by the Munyeru river, to the east of Chintapilly, we reach the Partial mines, standing on the left bank of the river. These mines also were formerly very rich and probably yielded the "Pitt" or "Regent" diamond, now in the French crown jewels. The workings, which are here in the loose decomposed mass of the diamantiferous bed and in the river alluvium, have been abandoned for a long period, although the diamantiferous bed is probably not exhausted; in 1850, according to Dr. Walker, only two mines of this group were being worked. Near to Partial, and belonging to the same group, are the old mines of Wustapilly, Codavetty-KalIu, &c.; the latter is said to have been especially rich, there being a legend to the effect that cart-loads of diamonds had been taken away. Here again the diamonds occur in sands, which are now no longer worked. </span>
<span style=" Still further east, on the left (north) bank of the Kistna, but at some distance from the river, are the Mu1e1i or Malavilly mines, situated between the village of the same name and that of Golapilly, to the north-east of Condapilly, and about six or seven hours' journey west of Ellore. Here pits fifteen to twenty feet deep are excavated in conglomeratic sandstone or in the surface debris derived from its disintegration. These sandstones rest on gneiss and belong to a somewhat later series of beds than does the Karnul series. The diamantiferous
stratum, which according to many observers is overlain by a bed of calcareous travertine, consists mainly of pebbles of sandstone, quartz, jasper, chert, granite, &c., as well as of large fragments of a limestone conglomerate, which show no traces of having been water-worn. All the minerals, which accompany diamond at Cuddapah are also present here, with chalcedony and carnelian in addition. These mines have been worked at least as recently as the year 1830, but the yield has since fallen off and they are now abandoned. In the district in which this group is situated, which lies partly in Haidarabad, the "Hyderabad Company" of English capitalists has acquired working rights. The Company's total output of diamonds in the year 1891 was 862 3/4 carats, valued at 15,530 rupees ($2,736,100). The annual output of the whole group of mines is at the present time little greater than this, being perhaps about 1000 carats. </span>
<span style=" To the north of the district just mentioned, diamonds are said to have been found at Bhadrachalam on the Godavari River. Their occurrence here is, however, doubtful, if not mythical, few if any stones having been found; the whole district is little known, and rendered extremely inaccessible by the thickness of the surrounding forests. Much richer and more important, at least in former times, is the fourth group of diamond mines now to be described. </span><span style=" script language=" .jpg --
<b>>Rich haul of diamonds in Anantapur</b>
(Times of India)
HYDERABAD: A high concentration diamond field has been discovered in Timmasamudram on the west bank of the Pennar river in Anantapur district.
K Palaniappan, director, technical coordination at Geological Survey of India, Hyderabad, told 'TOI' that the exploration carried out with advanced technology has yielded so many diamonds that they describe the field as having the highest concentration of gem quality diamonds so far discovered in Andhra Pradesh.Vakalapudi Srinivas Chowdary, a geologist involved in the exploration, said though Timmasamudram Kimberlite Pipe Four (TK4) could be the smallest in size- 14 metre deep and 6 metre wide- it is yielding 64 carat of diamonds per 100 tonnes of kimberlite material.
<b>Anantapur awaits the diamond rush</b>
HYDERABAD: If all goes well, Anantapur will emerge as a major diamond mining centre in the next two years. As per the initial findings of the National Mineral Development Corporation Ltd, there are locations in the district that have the potential for diamond mining.
The corporation would take two years to check the potential and zero in on the exact mining site. It is working on three locations in Anantapur — Anumpalle in Pamidi mandal, Venkatampalle in Vajrakarur and Chigicherla in Dharmavaram.Anumpalle has the biggest diamond-bearing pipe in the country in a marked area of about 1.5 sq km. Venkatampalle has one of the smallest pipes. "We have been working on the sites for the last three years. We have the prospective licence for another two years, during which we will have to complete our work and declare whether the location is viable for mining," NMDC's senior manager (geology) K Krishna Reddy said. While the area investigated in Venkatmpalle is spread in 0.75 sq km, Chigicherla site is in 7.89 sq km
<b>Discovery of diamond-bearing kimberlites in Kalyandurg area </b>
Dharwar Craton with two well-known kimberlite fields – the Wajrakarur Kimberlite Field (WKF) in Anantapur district, Andhra Pradesh and the Narayanpet Kimberlite Field (NKF) in the western part of Mahbubnagar district, Andhra Pradesh and the adjoining Gulbarga district, Karnataka, forms a prominent kimberlite province in India. Seventeen known kimberlites of the WKF are distributed mainly in three clusters, viz. (i) The Wajrakarur cluster; (ii) the Lattavaram cluster, and (iii) the Chigicherla cluster and some isolated kimberlite bodies1. Ground surveys based on conceptual modelling and characterization of the kimberlite indicator minerals recovered during reconnoitary traverses led to the discovery of a hitherto unknown cluster of diamond-bearing kimberlites around Kalyandurg within the Hagari drainage basin in the southern part of WKF .The area forms a part of the NNW–SSE trending, 500 km long and 25 km wide zone of post-tectonic granite called Closepet Granite. Two sets of mafic dykes trending NNW–SSE and ENE–WSW intrude the granite. The area is traversed by a number of NNW–SSE faults parallel to the regional trend of the granites and major ENE–WSW trending transverse faults.Kimberlites, emplaced in the cratonized parts of the earth’s crust are essentially controlled by major deep-seated faults/fractures, whose reactivation has a bearing on their emplacement. While these form the regional controls, fault intersections, splay faults around fold closures and resultant fractures form the most ideal local controls for kimberlite emplacement2,3. The kimberlites of WKF were emplaced around 1100 m.y. period4. Nayak and Burhanuddin5 related the emplacement of kimberlites, in Eastern Dharwar craton to the reactivation of major crustal fractures around 1100 m.y. period.
A conceptual model, based on the disposition of known kimberlites of WKF in relation to their geological setting and tectonic milieu, supplemented by critical evaluation of the data emerging from study of geological maps, satellite imageries and aerial photographs, was visualized for locating new kimberlites, which envisaged that kimberlite emplacements in this field were controlled by major ENE–WSW faults, passing through the closures of structural domes and reactivated around 1100 m.y period. Intersection of these faults with NNW–SSE faults/fractures formed the favourable loci for kimberlite search. Evidences of reactivation of these faults are recorded in the sediments of the Nallamalai Group of the Cuddapah Basin. Satellite imagery
studies indicated that the ENE–WSW faults hosting the kimberlites of WKF extend further west up to the Chitradurga Schist Belt in Karnataka cutting across the Closepet Granite which is believed to have been emplaced along a major NNW–SSE trending fault6. The area around Kalyandurg marked by the intersection of these ENE–WSW faults with NNW–SSE trending contact of the Closepet Granite with the gneisses and also faults/fractures parallel to it was considered favourable for kimberlite emplacement.
