"This résumé is so full of errors that we cannot but suspect that they conceal some design. The historian must have known that the Pitt diamond, one of the finest and most perfect of its kind, was produced at Gáni Partiál, and that the Koh-i-noor came from the so-called 'Golconda mines.' Again, Partiál, on the north bank of the Krishna, some fifty miles from the Bay of Bengal, is only one of many diggings in the vast area which I have before laid down, some being still worked, and the others prematurely, we must believe, abandoned.
"The student will do well to consult that valuable volume, the 'Geological Papers on Western India' (Bombay, 1857), edited by my old friend, Dr. Henry J. Carter. Here he will find detailed modern notices of a multitude of mines. John Malcolmson, F.R.S. (p. 6), treats of the diggings at 'Chinon on the Pennar,' and the Cuddapah mines (p. 6). Of the latter Captain Newbold says ('Geological Notes' p. 375), 'The diamond is found in the gravel beds of the Cuddapah district below the Regur,' the black, tenacious, and fertile soils of Central and Southern India. The same scientific officer, who died too early for his fame, describes (p. 67) the yield of Mullavelly (or Malavilly), north-west of Ellore, as 'occurring in a bed of gravel, composed chiefly of rolled pebbles of quartz, sandstone, chert, ferruginous jasper, conglomerate, sandstone, and Kankar, lying in a stratum of dark mould about a foot thick.' Both these geologists inferred the identity of the sandstone of Central with that of Southern India from the existence of the diamond at Weiragad, a town about eighty miles south-east of the capital. Malcolmson declared that the 'celebrated diamond mines of Partel (Partiál), Bangnapilly, and Panna, occurring in the great sandstone formations of Northern India, as well as the limestones and schists associated with them, exhibit from the latitude of Madras to the banks of the Ganges the same characters, and are broken up or elevated by granite on trap rocks, in no respect differing in mineralogical characters or in geological relations.'
"The Rev. Messrs. S. Hislop and R. Hunter, who visited and described the Nagpur mines, object to this assertion, and endeavour to prove that the 'diamond sandstone of the Southern Maharatta country is a conglomerate, reposing upon the arenaceous beds, which have never yielded the precious stone, nor are there any data to prove that the conglomerate derived most of its materials from that source.' Dr. Heyne contributed an excellent description of the mines of Southern India, especially those of Bangnapilly (p. 689); of Ovalumpilly, six miles from Cuddapah (p. 691); and of others in the Ellore district. This experienced geologist concludes, 'All the diamond mines which I have seen can be considered as nothing else than alluvial soil.' Major Franklin ('Geological Translation,' second series, vol. iii. part i.), who visited the mines of Pannah in Bandelkhand, before Victor Jacquemont's day, makes the diamond sandstone, between the Narbada (Nerbudda) and the Ganges, belong to the 'New Red'—apparently an error. Others have described the diggings east of Nagpur (Central Provinces) as having been opened in a matrix of lateritic grit. Dr. Carter ('Summary of the Geology of India,' pp. 686-691) connects the 'diamond conglomerate' with the Oolitic series and its débris, and he offers (p. 688) a useful tabular view of the strata in the mines of Bangnapilly, described by Voysey, and Pannah or Punna, by Franklin and Jacquemont. The most important conclusion is their invariable connection with sandstone.
"Dr. Carter's volume quotes largely from the writings of Mr. Voysey (Journal As. Soc., Bengal, second Report on the Government of Hyderabad), a geologist who maintained the growth of the diamond as others do of gold: he declared that he could prove in alluvial soil the recrystallization of amethysts, zeolites, and felspar. During his last journey from Nagpur to Calcutta he visited the diamond washings of 'Sumbhulpore,' in the Mahanadi valley, and he describes the gems as being 'sought for in the sand and gravel of the river,' the latter consisting of pebbles of clay slate, flinty slate, jasper and jaspery ironstone of all sizes, from an inch to a foot in diameter.
"We possess fortunately a modern description of the diggings, which, I have said, were visited successively by Major Franklin and by Victor Jacquemont. M. Louis Rousselet ('L'Inde des Rajahs,' Paris, Hachette, 1857), in his splendid volume (pp. 440, 443), gives an illustration and an account of the world-famous mines of Pannah, the Pannasca of Ptolemy (?), a little kingdom of eastern Bandelkhand erected in 1809. The Rajah sent a Jemadar (officer) to show him the diggings, which are about twenty minutes' walk from the town. The site is a small plateau covered with pebble-heaps; and, at the foot of a rise somewhat higher than usual, yawns the pit, about twelve or fifteen or twenty feet in diameter (about one hundred and eighty feet deep). It is pierced in alluvial grounds, divided into horizontal strata, débris of gneiss and carbonates, averaging thirteen metres. At the bottom is the diamond-rock, a mixture of silex and quartz, in a gangue of red earth (clay?). The naked miners descend by an inclined plane, and work knee-deep in water, which the noria, or Persian wheel, turned by four bullocks, is insufficient to drain; they heap the muddy mixture into small baskets, which are drawn up by ropes, whilst a few are carried by coolies. The dirt is placed upon stone slabs, sheltered by a shed; the produce is carefully washed, and the silicious residuum is transferred to a marble table for examination. The workmen, each with his overseer, examine the stones one by one, throwing back the refuse into a basket; it is a work of skill on the part of both men, as it must be done with a certain rapidity, and the rough diamond is not easily distinguished from the silex, quartz, jasper, hornstone (corundum), etc.
"Tradition reports that the first diamonds of fabulous size were thus found, and the system of pits was perpetuated. When one is exhausted it is filled up and another is opened hard by—a deplorable system, as one hundred cubic metres must be displaced to examine one, and around each well a surface of twenty times the area is rendered useless. Moreover, much time is lost by the imperfect way of sinking the shaft, which sometimes does not strike the stone.
"This diamond stratum extends more than twenty kilometres to the north-east of Pannah. The most important diggings are those of the capital, of Myra, Etawa, Kamariya, Brijpur, and Baraghari. The mean annual produce ranges between £40,000 and £60,000—a trifling sum, as the stones are the most prized in the world, and sell for a high price in the country. They are pure and full of fire; the colour varies from the purest white to black, with the intermediate shades—milky, rose, yellow, green, and brown. Some have been found reaching twenty carats, and the Myra mine yielded one of eighty-three, which belongs to the crown jewels of the Mogul. Of course, the real produce must be taken at double the official estimate, despite all precautions; such is the case everywhere. The Rajah has established an approximate average amount, and when this descends too low, he seizes one of the supposed defaulters and beheads him or confiscates his goods. He sells his diamonds directly to Allahabad and Benares, and of late years he has established ateliers for cutting. These are the usual kind, horizontal wheels of steel worked by the foot.
"Evidently here we have a primitive style, which has not varied since diamond-working began. Good pumps are required to drain the wet pits. Instead of sinking a succession of shafts, tunnels should be run along the veins of diamond-bearing rocks. Magnifying-glasses and European superintendence would improve the washing. I need hardly say that the yield would double in the hands of Brazilians or South Africans.
"The precious stone is still brought for sale from the nearer valley of the Krishna to Hyderabad. It occurs, I was assured, in a white conglomerate of lime locally called gar-ká-pathar, which must be broken up and washed. As it is found in a region of crystalline rocks, common sense would suggest tracing up the material to the places where it may have been formed; but this is never done. During our week's visit I was consulted by two Parsee merchants concerning the rudimentary tests of scratching and specific gravity. In fact, at Golconda, where the finest gems used to be worked, no one, strange to say, can now recognize a rough diamond.
"The 'Highlands of the Brazil' (ii. 113) has given a detailed list of the various stones associated with the gem; and specimens of the cascalho, or diamond gravel, the tauá, the canga, etc., have been sent to the Royal Society of Edinburgh by Mr. Swinton. It is advisable to remark that this association has everywhere been recognized. In Borneo we are told that 'the diamond is known by the presence of sundry small flints.' The gem-yielding pebble-conglomerate of India, not usually a breccia, as was proved by Franklin, Newbold, and Aytoun (loc. cit., p. 386), contains quartz and various quartzose formations; garnet, corundum, epidote, and Lydian stone; chalcedony and carnelian; jasper of red, brown, bluish, and black hues; and hornstone, a kind of felspar, whilst 'green quartz indicates the presence of the best stones.' Fossil chert is yielded by the limestone, and the highly ferruginous and crystalline sandstone produces micaceous iron ores, small globular stones (pisoliths?), and almost invariably fragments of iron oxide. Finally, there are generally traces of gold, and sometimes of platinum. At Hyderabad I was assured that such was the case on the Krishna river; but none of my informants had any personal knowledge of washing. Finally, Dr. Carter's 'Geological Papers' convinced me that the sandstones of the diamond area will be found to resemble the itacolumite—quartzose mica slate or laminated granular quartz, of Brazilian 'Minas Geraes.'