Almas, An., PERS., REIS. Kamala, Kumala, MALAY. Kin-kang-shi, . . CHIN. Intan, . . . . „ Jahalom„ . . . ' IIEB. Mass, PERS.
Hira, . . . HIND. Virum vachira kallu, TAM.
The diamond is a crystallized mineral. On account of its lustre and hardness, it is reckoned the most valuable of all precious stones. The form is cubical, frequently in twin crystals, cleavage highly perfect, rarely massive. The bulk of the forms are those of the octahedron, an octahedron having six planes on the edges, or a dodecahedron with rhombic faces. - Lustre brilliant adamantine. Colour white or colourless, occasionally with tints of blue, yellow, red, orange, green, brown, or black. Transparent to translucent when dark coloured. Fracture Conchoidal, H. 10, sp. gr. 3.5295 to 3'55. Exhibits vitreous electricity when rubbed. Index of refraction, 2.439. Becomes phosphorescent on exposure to light, and the smaller diamonds become phosphorescent by a much shorter exposure than required for those of a larger size. The diamond is carbon in its purest form, and its combustibility was ascertained by the Tuscan philosophers. About 30 per cent. of diamonds are under half a carat, and one in a thousand may be above 24 carats. Diamonds have been obtained in India, from very ancient times. Ptolemy's Geography, said to have been composed sixty years after the time of Pliny, mentions the diamonds found on the banks of the Sumbulpore river ; also speaks of Arcati (the capital of the Sorm or Sora - roandalum, from whence corruptly Coromandel), Mesolia (the dis trict which contains Masulipatam), and the river Cauvery under the name of Chabaris. Rennell supposes Punnah in Bundelkhand to be the Panassa of Ptolemy, and quotes the Ayin-i Akbari as naming Biragur on the west of Boad near the Mahanadi river, adding that there is indeed a mine of more modern date in the vicinity of Sumbulpore. Ptolemy's Adamas river answers perfectly to the Mahanadi ; and the district of Sabar, on its banks, is said by him to abound in diamonds. Tavernier visited the
Raolconda diamond mines at the confluence of the Kistna and Bhima rivers, which were also noticed by Cmsar Fralerick.;-adaci_both Tavernier and Benne11 notice the diamond mines of tho Pennar river, and near Gandicotta, also those of Colore (Kulur?) on the south bank of the Kistna, not far from Condavir.
The diamond mines of the Peninsula of India and Central India lie between lat. 13° and 25° N. They occur in irreguLar arid patches, sometimes basin-shaped, in hilly districts on the great elevated plains bordering the more considerable rivers that have an easterly and southerly course to tho Bay of Bengal. Diamonds of considerable size aro not rarely found in tho sands of these streams and of their tributaries ; but their geomnostic situs must he referred to the sandstone an sandstone conglomerates at Ovalumpilly ; Condapettah, in the Chinoor talnk on the banks of the Fermat., about miles from Cuddapali ; Lamdur and Panchatgapadu • at Banaganapilly on the Kurnool frontier ; at Rtimulucottah and other places in Kurnool, and at Munimadagoo, north of Ghooty.
Further to the north and east diamonds are found on the banks of the Kistna, iu the vicinity of Condapilly, in a plain formed by the alluvium of the river. Still further north, in the bed and alluvium of the Mahanadi river, especially at Sumbulpore, and about the mouths of the Hebe, Khelu, and Afaund streams. Diamonds are also found in the bed of the Godavery about Badra chellum.
To the north-west of the districts here noticed, are the diamond mines of Funnah in Bundel khand. They occur in a table-land covered by a reddish soil, which lies over a bed of rolled pebbles of the sandstone formation, in which the diamonds aro found.
The Kurnool geological formation of the modern geologists occupies all the low ground of the Khundair valley, in the middle of the basin, and another la.rge space in the Palnad. It consists of shales, limestones, quartzites, and, lowest of all, sandstones.