Northumberland and Durham. 83 



The quantity shipped from Stockton is on an average about 3000 

 tons per annum. The whole of the lead mines in Great Britain 

 are estimated to produce from 45000 to 48000 tons per annum. 



The minerals which occur in the veins of the lead-mine district 

 are the following. 



Ores of Lead. 

 Galena. — Massive. 



Crystallized in cubes, or with all the angles or edges of 

 the cube truncated or bevelled in various degrees, or in 

 oc'ohedrons. 

 Occurs in cavities with fluor, and calcareous spar, pearl 

 spar, quartz, sulphate and carbonate of barytes, iron 

 pyrites, sparry iron ore, blende, calamine, &c. 

 Crystallized in 14-sided figures, imbedded in soft brown 

 marly clay like umber, which effercesces with acids: 

 from Kilhope mine at the head of Weardale. 

 Reticulated ore from Allenheads and Aldstone moor. 

 Steel grained ore from the Teesdale, Weardale, Allendale, 



and Aldstone mines. 

 Specular ore or slickensides in a matrix of calcareous spar.j 

 from Allenheads. 

 Aniimoniated Lead ore — -From Dufton mines. 

 Lead Ore with excess of Sulphur.- — This ore is earthy, of a bluish 

 grey colour, 2nd so highly inflammable as to take fire 

 and bum on being held in the flame of a candle. From 

 Dufton mines. 

 Carbonate of Lead. — Massive. Colour grey. Lustre adamantine. 

 From Flow-edge mine Aldstone moor. 

 In 4-sided tabular crystals, bevelled on the terminal planes : 

 lustre adamantine. From Allenheads and Aldstone moor, 

 L 2 



