1865.] MACFARLANE— GEOLOGICAL SKETCH OF ROSSIE. 273 



calcspar occurs, containing copper pyrites in small grains scattered 

 through it, the quantity so small as merely to bring the contents 

 of the best pieces up to -J per cent. The strike is, however, such 

 as to intersect the fahlband, and it might be important to explore 

 it where it does so, as its character might there alter, and possibly 

 its contents in copper pyrites increase. This fahlband was traced 

 altogether a distance of three quarters of a mile on the strike, 

 but had time been devoted to its exploration, it would probably 

 have been found continuous along a much greater distance. 



Traces of fahlbands, or at least of brown-weathering rocks, occur 

 at many other points, and there would seem good reason for sup- 

 posing that there exist in Rossie a tolerable number of such fahl- 

 bands running rudely parallel with each other, the tracing out of 

 which, and their exploration for minerals of value, might be 

 attended with important results. 



In the south-eastern part of the town of Rossie, the very extensive 

 deposits of iron ore occur, which formerly supplied the Rossie iron 

 furnaces, and the working of which has very lately been resumed. 

 Open workings have been carried on at four different points, called 

 respectively the Old Caledonia, New Caledonia, Kearney and Keene 

 ore-beds. The first-named working consists of several excavations 

 made into the face of a ridge consisting mainly of iron ore. The rock 

 which forms the most elevated part of this ridge is probably a part of 

 the Potsdam sandstone. The upper layers are comparatively soft and 

 of undoubted detrital character. As it approaches the underlying 

 iron ore, however, it becomes excessively hard, assumes almost the 

 vitrified appearance of some quartzites, and becomes slightly mixed 

 with ore. A little below this, and filling the interstices between 

 fragments of ore, a brown-spar is sometimes found, which seems to 

 be a mechanical mixture of the carbonates of iron and lime in the 

 proportion of 16.2 per cent of the former to 83.8 per cent of the 

 latter. Beneath the indurated sandstone lies a great mass of 

 iron ore which is at least forty feet thick vertically. It consists 

 of compact amorphous hematite, with which more or less silicious 

 and calcareous matter is intermixed. Occasionally .cavities are 

 found in the interior of the ore filled with various minerals, and 

 one of these I observed contained calcspar and transparent rhom- 

 bic prisms of heavy spar. In the richest and densest pieces of 

 the ore small fissures occur containing graphite, and indeed this 

 mineral seems to be disseminated through all the ore in more or 

 less considerable quantity. A specimen of this best ore contained, 

 on examination, 



Vol. II. s No. 4. 



