GEOLOGY 



LEAD AND LEAD MINING 



The large number of old mines bears witness to the vast amount 

 of mining which has been done in Derbyshire. The majority of mines 

 have been worked out or abandoned through the difficulty of getting 

 rid of water, the expense of obtaining the ore, and the great fall in the 

 price of lead. The only mine at which any quantity of lead is being 

 raised is the Mill Close near Darley Dale. It is in the upper beds 

 of Mountain Limestone. 



The oldest mine in the county is probably the Odin near Castleton, 

 which is reputed to have been worked by the Danes. The Romans 

 raised and smelted ore in Derbyshire, and left traces of their work in 

 pigs of lead with Latin inscriptions. 



The lead mining industry in Derbyshire is governed by curious 

 customs and rights which have existed from time immemorial, and were 

 confirmed by Acts of Parliament passed in 1851 and 1852. 



In certain parts of the county any one may search or dig for lead 

 ore without asking for the owner's permission, and the owner or occupier 

 of the land cannot claim compensation. This is subject to the condition 

 that the miner finds ore and pays a dish to the barmaster. The miner 

 is entitled to sufficient surface for his hillock, a way to the highway 

 most convenient to the mine, and waterway to the nearest stream of 

 running water. The only compensation the owner gets for the loss is 

 the right to sell any other mineral except lead which the miner may 

 bring to the surface. 



Galena is the ore of lead which has been mostly worked. It is 

 found in rakes, pipes and flats. 



A rake vein is generally an almost vertical fissure in the limestone. 

 The ore usually occurs in ribs with layers of calcite, barytes or fluor 

 arranged more or less parallel to the walls of the rake. Sometimes it 

 is found in isolated cubes in association with calcite or barytes. 



Pipes veins are irregularly shaped cavities or pockets in the lime- 

 stone generally parallel to the bedding planes, and are often connected 

 by a crack filled with clay or spar called a leader. 



They vary in size, and may be considered as the widening out of 

 a rake or of a serin, which is a string of ore branching off from a 

 rake and forming smaller veins. 



A flat is not so common as rake and pipe veins. It is generally 

 found along the junction of two beds, and consists of a low flat chamber 

 with the roof and floor separated by only a few feet. 



The lodes are richer and more numerous in the upper than in the 

 lower beds of limestone, and most of the rich deposits of ore have been 

 found in the beds of limestone immediately below the Yoredale Shales. 



In addition to galena the following ores of lead have been obtained 

 in small quantities : mimetite, cerussite, pyromorphite and phosgenite. 



Small quantities of copper ore, black oxide ot manganese ('wad'), 

 haematite, yellow and red ochre have been worked in the limestone. 



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