552 J. G. H. GODFREY ON THE GEOLOGY OF JAPAN. 



The total annual production of silver in Japan was estimated by 

 me in 1874 at 2600 kwme = 315,900 oz. troy. 



(d) Gold. — Most of the gold produced in Japan is derived from 

 auriferous -silver ores ; it occurs by itself in the metallic state, and 

 in sufficient quantity to be collected by a washing process only in 

 a few localities. The most important auriferous quartz-veins occur 

 in the provinces of Koshiu, TJgo, and Satsuma. 



At Homura (prov. Koshiu) numerous thin quartz-veins of very 

 limited extent are found interbedded in a hard clay-slate. The 

 metallic gold is here associated with small quantities of iron- and 

 arsenical pyrites, blende, and galena. Owing to the hardness of the 

 containing rock, underground mining has been carried on only on a 

 very small scale, and the work has been confined chiefly to the 

 washing of the alluvial deposits in the proximity of the mines. The 

 ground in the neighbourhood of the quartz-veins is much broken up, 

 and consequently rapidly disintegrated by atmospheric influences. 



At Ooguzu (prov. Ugo) a quartz-vein about 2 feet wide, running 

 nearly N. to S. and dipping 60° W., and numerous cross veins of 

 smaller size, bearing N.E. to S.W., occur in a greenish soft clay- 

 stone porphyry (probably decomposed rhyolite). 



The metallic gold is here associated with copper- and iron-pyrites. 

 A dark greyish mineral, probably sylvanite, often accompanies the 

 metallic gold. These veins have been mined for many years past, 

 and the gold is collected by stamping the ore and subsequent wash- 

 ing and amalgamation. 



AtSerigano andYamagano (prov. Satsuma) numerous quartz- veins 

 of greatly varying thickness, running E. to "W. and dipping slightly 

 N., are found in a rock resembling decomposed propylite. Usually 

 the gold occurs therein alloyed with silver ; and this alloy sometimes 

 partially fills out cavities in the veinstuff with thin foils studded 

 over with small cubical crystals of the same alloy. 



Most of the auriferous quartz-veins in Japan are very irregular 

 in their character and very changeable as regards their yield in gold. 

 The total production of gold per annum in Japan was estimated by 

 me in 1874 at 12,150 oz. troy. 



(e) Iron— About two thirds of the whole production of iron in 

 Japan is derived from the treatment of the sand of magnetic iron- 

 ore. The principal deposits of this iron-sand are found along the 

 eastern and southern shores of the main island (Nippon), and usually 

 they appear to have been derived from the decomposition of the 

 neighbouring granitic rocks. A harder granite, less liable to disin- 

 tegration, is frequently found intruded into these granitic rocks, and 

 with the lapse of time is left behind in the shape of steep walls. 



Massive magnetic iron-ore is also of frequent occurrence ; the 

 most important deposits of it are found in the northern part of 

 Nippon in the province of Rikuchu. They occur in a mountain- 

 ridge running N. to S., and have usually the same bearing, but are 

 of an irregular nature and vary in thickness from 50 to 200 feet. 

 Along the direction of the strike, outcrops have been found for a 



