74 NOTES ON THE MINERALS FOUND NEAR BRISTOL. 



small green crystals encrusting the surface of the blocks of stone. 

 On charcoal, before the blowpipe, a metallic bead is easily 

 obtained. 



LEAD. 



This metal is nearly always found as Galena or sulphide. It is 

 extremely common throughout the whole district wherever the 

 limestone is seen. As before mentioned, the Mendips were 

 celebrated from very ancient times for the abundance of Galena. 

 Large quantities have been noticed on the rocks at Westbury and 

 Shirehampton -, and it may be actually picked out from the hedge- 

 side at Fishponds. The Galena is always found in cubes or some 

 slight modification. In the Clevedon dolomite the configuration is 

 very peculiar. The cubes are so built up that the crystals resemble 

 railings, stiles, gates, &c., or like some of the geometrical puzzles 

 of children. 



All the Galena in this district is argentiferous, containing about 

 0.02 per cent, of silver. Another ore of Lead is peculiar to the 

 Mendip Hills, and is called, therefore, Mendipite. It is an oxy- 

 chloride (2 PbO, Pb CI2), a compound of oxide of lead and 

 chloride. It is found in beautiful yellowish- white, semi-transparent 

 crystals, and is composed of — 



Plumbic oxide ... ... ... 60.18 



Plumbic chloride ... ... ... 39.82 



100.00 



It is readily soluble in nitric acid, and easily reduced on charcoal. 

 It is very rare : not a specimen has been collected for many years. 



MANGANESIVM 



Is often found as dioxide, — sometimes as a deposit, sometimes as 

 fine crystals enclosed in quartz. It is also a common companion 

 of haematite, as shewn in the analyses of that mineral. When 



