The Breadalbane Mines. 205 



below show the extent of the workings, which were never 

 carried on very extensively as the mine was hardly ever 

 able to pay its own expenses. The ore, when stamped and 

 dressed, contained very little copper, one analysis by Professor 

 Andrew, Glasgow, giving 3'58 per cent, copper and 30"28 per 

 cent, sulphur, and the great cost of transporting the metal 

 when smelted to the Glasgow market further reduced or totally 

 swallowed up any small profits which might have been made 

 had the present Oban and Callander Eailway been in existence. 



5. Remarks on II. and III. — The Ore deposit of Tomna- 

 dashan is essentially different from that of Tyndrum, but 

 belongs to a type nearly related to that which includes the 

 chrome ironstone of Corrycharmaig. In the former case the 

 ore is in a vein in stratified rocks through which water could 

 freely circulate, but in the latter it is disseminated throughout 

 a rock which is not stratified, but crystalline or massive in 

 character and igneous in origin. 



The ore deposit of Corrycharmaig belongs to von 

 Groddeck's type "Wooded Peak," named from a mountain in 

 New Zealand, which forms part of a great tract of serpentine 

 80 miles long and 1 or 2 miles broad, and consists largely of 

 this ore. The serpentine and chrome ironstone are both of 

 the same age. The original olivine, augite, or enstatite rock, 

 consisting largely of a magnesian silicate, contained also iron 

 and chrome mineral ingredients, and in the process of 

 serpentinising, the magnesian silicates became hydrated, and 

 the other minerals underwent a different change. The 

 original iron in the rock became separated out as magnetite, 

 while the chrome-minerals, picotite, chromediopside, etc., 

 were decomposed, and the chromium combined with the iron 

 to form chrome iron ore, which is isomorphous with magnetite. 

 It is thus useless to expect to find a true vein at Corrychar- 

 maig, as the chrome ironstone does not occur in veins, but is 

 disseminated throughout the serpentine in more or less con- 

 centrated aggregates, and mining in such a deposit must be 

 always more or less precarious in character. 



The same remarks are generally applicable to the copper 

 deposit of Tomnadashan. It belongs apparently, most nearly, 

 to a related species named by our authority "Type Med- 



