CORUNDUM Kin-kang-shih, . . Cum. Samada, . . . GIJJ. Adamantine spar, . ENG. K-urund, . . . HIND.
Several substances, differinff considerably in colour and sometimes in form:but nearly agree ing in composition are classed together under the name of kurundu 'by the natives of India. This mineral is, with the exception of the diamond, the hardest substance known. It is generally of a, pale grey or greenish colour, but sometimes of red and brown tints. It is found in India, China, and in some parts of Europe. The Indian variety is whiter than the Chinese, and is considered the purer. In India, diamond dust is very rarely used in polishing gems, marbles, and metals, corundum being the chief material employed. This mineral is found in granite, or the detritus of granite rocks in the Mysore country and in the neighbourhood of the S.W. Ghats. Though excessively hard, it is by no means tough,—it flies in pieces after a few strokes of the hammer, and is easily pulverized in a mortar. The natives generally powder it on an anvil or stone, keeping it from flying about by a collar of cotton rope. The line particles are separated 'from the coarse by sifting ; the European process of lixiviation is not seemingly resorted to. For sharpening swords or burnishinu metals, it is generally used like a whet stone or b6urnisher ; for polishing gems, it is either made up into a cake with lac, or into a paste with oil or grease. It is never employed for the manu facture of emery paper or anything resembling it. For polishing inarble or other stone, it is used in two forms, viz. that of a cake of about eight inches long, three across, and two deep. This is used by an individual in the hand. For heavier purposes, a cake a foot square or so is employed, placed in a frame. Two rnen work at this, and the reducing process is very rapidly accomplished by it ; it is in fact a file with a lac body and corundum teeth.
The corundums of the Madras Presidency are well known to the people, who use them in mass or mixed in lac they are used by cutlerS, etc., in the form of diLs for laps, or wheel grindstones ;• also, in the form of whets, and hones, and rag stones, for sharpening the finer and coarser cutting implements used by farriers, etc. The first speci mens sent to Europe were forwarded by Dr. James Anderson to Mr. Berry, a lapidary in Edinburgh, as the substane,e used by the people of India to polish masses of stone, crystal, and all gems, except the diamond, and it was then examined by Dr. Black, who named it adamantine spar.
The sites where corundum occur are— Nammaul, Viralimodos.—On the north bank of the Cauvery, in the Permutty taluk.—Newbold. Sholasigamany (probably Scholaserameny).
Trichingode taluk, near the village in a low hill, in great abundance.—Newbold.
Caronel, Aupore, Mallapollye, and at various localities up the river Cauvery as far as Corcorambodi in Permutty, where it is dug by the natives in the fields, and remains of many ancient excavations are to be tmced.—Newbold.
Gopaulchetty pollium, 50 miles north of Salem. Yalauerry.
Coundapady.
French Rocks. —Captain Loudon.
Golbushully, in the division of Nooghully.—Newbold. Kulkairi, in the division of Chinrayapatam.
Burkunhulli, in the division of Cbinrayapatam.—Newb. Kundeo, in the division of Cbinrayapatam.—Newbold. Yedgunkul,in the division of Chinrayapatam.—Newbold. Norhik, in the division of Narsipur.—Newbold. Deysani Carbonhully, in the division of Banawaram. Appianhully, in the division of Harnally.—Newbold. Nullapardy, on the road to Bangalore, Mysore. Mundmm, in the Astagram division.
Cuddoor, in the Nuggur division.
Nuggur, in the Nuggur division.
It occurs also at Gudjelhutty in Cohnbatore, at the ,Tapoor Ghat in Salem, at Chennimully in Coimbatore, and in Cuttack. At Namaul and at
Viralimodos on the north bank of the Cauvery ; in the Permutty taluk, Salem district, it occurs embedded in gneiss and a greyish earth, resulting in part from the disintegration of that rock. It is found in great abundance in a low hill near the village of Sholasigamany, Trichingode taluk, Carona], Aupore, Mallapollye, and at various localities up the river Cauvery, as far as Corco rambodi, where it is dug for by the natives in the fields ; and there are the remains of many ancient excavations still to be traced. The caste usually employed in collecting it is the Vittaver. At the Madras Exhibition of 1855, Mr. Rohde exhibited specimens from Guntur, and remarked of them that experienced jewellers would pick out stones suited for common jewellery from it, and the refuse cannot be worth less than £15 and ton at home. From Hyderabad was received a very excellent sample of picked stones, possessing an irregularly crystalline structure. Professor Thomson mentions (Mineralogy, i. 213) that fibro lite is found accompanying crystals of corunduin in the Karnatic, and that it is a component part of the granite which is the rnatrix of the corundum of China. Professor Jameson, in his Geognosy of Peninsular India (Ed. Cab. Lib. No. viii. p. 349-50), states that the corundum of Southern India occurs embedded in granite and sienite in the district of Salem, in the Madras Presidency, associated with Cleavelandite Indianite, and fibrolite; but near Gram at Golh'ushully and Kulkairi, at which good corundum is obtained, the mineral occurs in decomposed beds of a talcose slate, to which gneiss is subordinate, associated with nodules of indurated talc, and of a poor quartzy iron ore ; asbestos, chlorite, actinolite, _and_ schorl were found in the talcose slate. Newbold mentions that in the Salem district, also, this mineral occurs embedded in gneiss and a greyish earth, malting in part from the disintegration of that rock. Rubies, sapphires, etneralds, and topaz have from time to timo been discovered in many of the corundum localities just enumerated, associated with this mineral, particularly in the gneiss at Viralimodos and Sholasiramany in tho Trichingode taluk and at Mallapollye, though, comparatively speaking, rare. The formation around Gram is gneiss associated with protogene. Proceeding from it in a westerly direction, the northern shoulder of the insulated range, south of the village of Bella daira, running nearly north and south, is crossed, and the soil suddenly changes from a light sandy colour to a deep red. The surface of this soil is covered with fragments of a ferro-silicious schist, with quartz in alternate layers. The natives have a tradition that gold was formerly got from this hill, which is not at all improbable, as it is found in similar gangue near 13aitmungalum. . The corundum mines of Golliushully lie four or five miles north-east of this place, and those of Kulkairi about a mile farther. The surrounding country is a succession of smooth, slightly convex plains, except to the south-east, where the gneiss rises above the soil in a rocky ridge, terminating in a knoll about 700 yards to the east by south of the mines, to which it descends, rising again into a slope to west north-west of the mines, on which lie fragments of a light brown compact quartzy iron ore. Nearly at the bottom of this stone are the mines, from which the ground descends on both sides to the north-west to a tank, and towards the south-east to the village of Golhushully, about a mile distant.