56 ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 



Cerium is one of the rarest of the elements hitherto dis- 

 covered, existing, so far as is yet known, in the very rare mineral 

 Churchite, of which only two or three specimens have ever yet 

 been found.* 



GrROTJP 7. Gold, Silver, 



Gold. I am not aware that this metal has ever been 

 detected in the rock-masses away from veins or cross-courses, but 

 as the same may be said of most of the richest gold regions, 

 the negative fact is not perhaps of much theoretic import- 

 ance. Few of the metallic ores and gozzans, however, are 

 absolutely free from gold, and in some instances it has been 

 extracted from them at a profit. 



Gold, in the metallic state has been found, but only in small 

 quantities, in several of the cross-courses, and in particular at 

 North Molton in Devon, at Wheal Sparnon in Eedruth, and in 

 Woolf's cross-course in Breage. It probably exists in many 

 other cross-courses, and perhaps in some of the veins (though if 

 so, it has always been overlooked), for particles of gold have been 

 found in most of the tin-streams of the district : in a few 

 instances, nuggets, of an ounce or more, have been met with. 

 And as most of the iron and copper pyrites, and some of the 

 other metallic ores, contain traces of gold,' the aggregate must 

 amount to a very considerable total, though very little of this 

 has ever been extracted by the smelter. 



Silver is much more abundant than gold, for though it has 

 not yet been detected in the rock-masses, it occurs in paying 

 proportions in all the lead ores ; in many of the ores of copper 

 and zinc; and in some of the gozzans. Occasionally, rich pockets, 

 worth thousands of pounds, have been found in cross-courses near 

 their intersections with right-running veins, especially in the 

 Hayle and Gwinear mines ; at Wheal Ludcott and Herodsfoot, 

 near Liskeard ; and on several mines in the southern flanks of 

 Kit Hill ; as also at Combe Martin in N. Devon. 



The earliest accounts of silver from N. Devon (ComBe 

 Martin and Beeralston) date from the year 1293, when Wm. de 

 Wymundham, the king's factotum, accounted to the treasury for 



* The almost equally rare element heryllium has also occurred in Beryl, and 

 ^s Danalite, each of which contains considerable proportions of the earth berylla, 



