93 mallet: coal-fields of the naga hills. 



which has percolated through the ferriferous beds of the coal-measures, 

 has cemented gravel or angular fragments into a compact rock. Some- 

 times the oxide is tolerably free from foreign matter^ and is sufficiently 

 rich for use as an ore. 



The ferruginous beds of the Tipam group have been already men- 

 tioned (p. 28J. In mineral character and geological position they resemble 

 the deposits of Lohargarh ia the Darjiling district,"^ and of Kaladhungi 

 and Deh-Chauri in Kumaon^f but they are poorer as ores than the latter. 

 Samples of the more highly ferruginous portions from Dholbagan and 

 Naphuk yielded respectively 35"2 and 32'6 per cent, of iron, but the 

 average amount is considerably less. 



In former times both descriptions of ore^ but more especially the 

 clay-ironstones, were worked extensively by the Assamese, and the re- 

 mains of their pits and the slag from their furnaces are still to be seen. 

 Tirugaon and Hattighar appear to have been two of the most important 

 places of manufacture, and thirty or forty workshops are said to have 

 been established there at one time. But even before the_ incursion of 

 the Burmese, the industry had greatly decreased on account of the dis- 

 turbed state of the country; and, according to Colonel HannayJ, the 

 ironworkers and smiths, who numbered 3,000 during the most flourishing 

 period in Upper Assam, did not exceed 100 after the invasion. When Mr. 

 Bruce visited the SafFrai valley in 1828, clay-ironstone, which was got by 

 sinking pits to a depth of 10 to 40 feet, was being smelted at the hill east 

 of Tirugaon. The raw iron was worked up into dhaus which were ex- 

 changed with the Nagas for the produce of their hills. According to Mr. 

 Robinson§, the manufacture of iron in Upper Assam was all but extinct in 

 1841, the causes that led to its abandonment being the injudicious taxes 

 levied on the ore by the Raja, and the under-selling of the home-made iron 



* Vol. XI, p. 65. 



t Records, Geological Survey of India, Vol. VIT, p, 18. 

 X Journal, Asiatic Soc, Bengal, Vol. XXV, p. 330. 

 § A Descriptive Account of Assam, p. 34. 



( 360 ) 



