342 Economic Geology of Assam. [No. 4. 



the Dora Panee. The rock is more easily frangible and appears to 

 contain more magnesia. Ditto ditto. 



33. Primitive limestone. — This rock is in situ in the first ranges 

 of the Upper Brahmaputra from the Dehong to the Brahma Koond. 

 The specimen is a good sample of the mineral as it might be 

 required for purposes of ornamental work, particularly for pave- 

 ments and table slabs. Boulders of the limestone for mortar pur- 

 poses can be procured in any quantity during the dry season. The 

 boulders of a large description of this, and the magnesian limestone, 

 and the variety passing between serpentine and carbonate of lime 

 with handsome granite, are found close up to the Northern moun- 

 tains, but they could only be brought into use for ornamental work 

 by having slabs cut on the spot which might not be a very difficult 

 matter, provided protection could be given to the workmen. 



34 and 35. Shell limestone. — From under the Namber falls. This 

 is in large quantities and only requires to be quarried. 



36 and 37. Limestone. — Found associated with Nos. 35, 36, and 

 decomposing felspar and slaty clay. These limestones in their 

 various beds, of which the extent is quite unknown, probably contain 

 the decomposing power which affects the granite and felspars in the 

 same manner as on the Upper Brahmaputra. 



38 and 39. Iron. — Smelted from the ore (oxide of iron sand) 

 washed from the plastic clays of Golaghat and Gilikha in the same 

 district. These ores have been deposited no doubt along with the 

 clays from the breaking up of granitic rocks under the influence of 

 water, vide specimens, Nos. 26 and 27, the latter containing a quan- 

 tity of metallic sand. But it is evident that in course of time, what 

 was originally magnetic and non-magnetic iron sands, has become 

 oxidized and altered. The appearance now being that of natural 

 exuviae. Both these ores are found in extensive beds, throughout 

 the Golaghat division inland, as well as on the banks of the Dhun- 

 seree river at Golaghat, and Dehing Gohainghat. The natives seem 

 to think that the resources of these ores are inexhaustible, but this 

 requires investigation. The quality of the ore is considered good, 

 and, even under the rude processes adopted by the iron smelters, the 

 manufactured iron ought to undersell that of the Cossyah or codal 

 iron, if not the English bar iron, though the convenient form, of 



