The Breadalhane Mines. 196 



S.W. of Eas Anie. Between these two places the vein is in 

 a true fissure with a S. 45° W. course. The Coninish vein 

 may possibly be a south-western prolongation of the quartz 

 reef which, towards the north, is quite barren. 



3. Distribution of Ores.— The working plans and reports 

 relating to the Tyndrum mines kept in the Breadalbane 

 Estate Office show the ore in the hard vein to be distributed 

 in four broad parallel bands, which run diagonally over the 

 plane of the fissure at an inclination of 30° to 40°. The 

 bands are shown on Eig. 3, which is reduced from the mining 

 plans ; between the shaded portions of the sections the ore 

 does not altogether disappear, but becomes poor and unwork- 

 able. 



4. Composition of Veins (1.) Ores.— The three veins 

 resemble one another in having the same mineralogical com- 

 position. Argentiferous galena is the chief ore, while zinc- 

 blende occurs in smaller quantity at each locality. The 

 blende was never used, but was thrown aside with the 

 " deads," and the quantity to be seen in the rubbish heaps at 

 the mouths of the various levels shows it to have constituted a 

 considerable proportion of the available ore. The galena is 

 of the ordinary type, with bright metallic lustre and perfect 

 cubical cleavage, but in the clay vein it passes into the com- 

 pact or cryptocrystalline variety, known locally as "steel 

 ore." When the clay vein leaves the fault and runs into the 

 schists it becomes split up into small strings, and the ore 

 deteriorates in quality, becoming disseminated through the 

 surrounding rock. 



A recent assay by Beringer of Cornwall of a sample of ore 

 from the western slope of Tyndrum Hill gave 



Lead, 287%. 



Silver, 1 oz. 6 dwt. per ton. 



The galena from the Coninish mine has a much higher 

 percentage of silver, and is generally a richer ore. The 

 average of two assays by Napier of Glasgow in 1863 from 

 the Beinn Lui and Beinn Chuirn levels gave 



Lead, 58%. 



Silver, 8 oz. 6 dwt. per ton. 



