109 



Some o£ the lead-bearing minerals are among the most beautiful 

 in Kature. Of these may be mentioned crocoisite^ loidfenife, 

 pjjromorpliite, and cerussite ; they are all very fragile. 



Arsenate and chloride of lead ; 886, (var. campylite). Europe. Mimetite, 



Lead sulphide, 3500, 7417 ; large cubes from Joplin, Missouri. Galena. 

 Joplin is a famous American zinc and lead mining district ; fine 

 crystals of zinc blende are also found in the mines (see case 87). 

 Lead-zinc ores from Wisconsin ndll be found in case 104. 



1300, Weardale Lead Mines, England ; cubic crystals, showing 

 faces of the octaliedron well, associated with fluor and chalybite. 



8508, Wheal Fortune Mine, Northampton, West Australia ; 

 cubic crystals, showing faces of the octaliedron. 



848, Alston, England ; somewhat similar to the Wheal Fortune 

 specimen. 



1301, Weardale, England ; crystallised with calcite. 



6252, Nanty .Grarn, Wales ; octahedral crystals. 



457, Carmarthenshire, Wales ; showing cubical cleavage and 

 octahedral faces, associated with the dog-tooth variety of calcite. 



469, Derbyshire, England ; with fluor. 



7989, Eutland Cavern, Matlock, Bath, England ; a lead mine 

 worked by the Eomans. The specimen has been taken from the 

 •old workings. 



COPPER. Cases 84, 



The Copper-Field of the Lake Superior District is one of the 103, 

 , . , 1 • c • 1 • . (i^ part). 



most important in the world, and is ot exceptional interest from 



the very peculiar nature of the deposit, and from the depth to 



which mining operations have been carried — over a mile. The Lake Superior. 



ore consists principally of native copper, and occurs, not in lodes 



or veins, but scattered through conglomerates and melaphyres of 



early Palaeozoic Age. The formation consists of a succession of 



lava flows and of sedimentary conglomerates and sandstones, 



native copper having been deposited in the cavities of the 



