8 EDWIN GILPIN ON THE 



peroxide up to fourteen per cent, of its total constituents. Some encrusting fibres are 

 mangauite, and part of the manganese is present iinder the form of wad, of which Mr. 

 H. Louis gives the following analysis : — 



Manganese peroxide 67-10 



Manganese protoxide 10 • 67 



Water 9-37 



Copper protoxide -88 



Iron protoxide 4 • 09 



Alumina. "67 



Nickel and cobalt oxide '65 



Lime 2-49 



^lagnesia trace 



Silica 4-08 



100-00 



The occurrence of this ore in the pre-carboniferous rocks is interesting-, as showing 

 its original wide distribution, and as possibly indicating the sources of part of the more 

 recent ores of economic value. Pyrolusite is the only ore of manganese which has hitherto 

 been mined to any extent in Nova Scotia, and it is known to occiir in i^re-carboniferous 

 strata at several points. Between Halifax and "Windsor, near Mount Uuiacke, pyrolusite 

 is found in small pockets and veins penetrating granite, and in quartzites of the auriferous 

 Lower Cambrian of the Nova Scotia Atlantic coast. It occurs in veinlets in the granite 

 of Musqu.odoboit, and as small irregular seams in the granite of Shi^i Harbour. In the 

 hills south of "Wolfville, in King's County, the same ore is found in quartzites and slates, 

 presumably of Upper Silurian age. In the trias of the same county, the ore is met in a 

 bedded form near Cornwallis and Wolfville, and in the triassic trap it is said to occur 

 lining cavities, in association with zeolites, etc. 



We, however, find these ores most abundantly in the Lower Carboniferous marine 

 limestone formation. This horizon forms one of the widest spread, and most strongly 

 marked of the divisions of the Carboniferous period. It is met in King's County, in 

 Hants, Cumberland, Colchester, Pictou, and Antigonishe, and in the four counties of 

 the Island of Cape Breton. The measures of this division, comprising sandstones, shales, 

 grits, and limestones, with beds of gypsum and marl, sometimes rest directly on the pre- 

 carboniferous strata, and at many points are separated from them by the lower, or false 

 coal-measures, or by beds of conglomerate, according to the conditions of the period of 

 accumiilation. The limestones and gypsums occur, apparently, at no fixed horizon in this 

 division. Dr. Dawson, in his " Acadian Geology ", has divided the limestones into five 

 groups, characterized respectively, so far as the subject has received attention, by a pre- 

 dominance of certain fossil forms. In his supplement to the second edition, he proposes 

 to subdivide the lowest grovip by distinguishing a certain manganiferous limestone, 

 which appears at many points to form the basis of the limestone formation, strictly so 

 called. This limestone at Salmon River, Cape Breton County, Spriugville and New Laiug, 

 Pictou County, Chester, Maitland, Tenny Cape, Windsor and Onslow, seems to underlie 

 the gypsum beds, and generally to be associated with manganese. The following 

 analyses by the writer show the character of some of these limestones : — 



