î) 4 Iwasaki : 



veins, which traverse the rocks everywhere. The quartz veins some- 

 times produce very rich gold, but it is most hopeful when the gold 

 forms placers. The placers may be divided into two distinct 

 kinds, original and alluvial. The former is seen on the surface of 

 the mountain region, forming the primary soil. The latter forms 

 the placer beds in the valley. The bedded deposits are found in the 

 form of successive river terraces, the highest and most promising 

 measuring about 200 ft. in height; the next is on a hillside and is 

 :about 80 ft. high ; while the lowest is only (> ft. from the valley 

 level and forms part of valley ground. These terraces cover more 

 than several hundred acres, and form horizontal strata of gravels 

 'Composed of pebbles of amphibolite, ]:>hyllite, quartz and andésite 

 cemented Ijy reddish clay, sand of the above stated rocks, and 

 limonite pseudomorph after pyrite. The conglomerate becLcontains rOA-^A 

 gold in the high proportion of from 3/1,000,000 to 9/100,000 or " 



1/100,000 on the average and measures from 6 to 120 ft. in thickness. 

 The gold grains are similar in form to those from old veins, and 

 may be classified into two groups, granular and crystallized. The 

 «colour of the granular gold is very fine, being like pure gold, and 

 is much larger in size usually measuring as much as 3 mm. in 

 diameter. Gold nuggets weighing 131 gr. and 67 gr. were once 

 found in the valley. The peculiarity of this granular gold is that it 

 is of a flattened form with cracks in it. The cr^^stallized gold 

 thought to be of a secondary origin is inferior in grade, and usually 

 «mailer in size, being not quite 0.5 mm. in diameter. The com- 

 paratively large size and flattened form of the granular gold is 

 explained by the fact that the gold was formed in amphibolite or 

 other crystalline schists in old time and subjected to intense 

 mountain-making force during the metamorphosis of these rocks. 

 The ore-bringer of this gold is not yet definitely known; but it is 

 probable that the amphibolite is a rock metamorphosed from the 

 diabase or like rocks which brought up the gold from the interior 

 <Â the earth, thus doing the work of the ore-bringer itself. 



8. The Kosaka Province. 



This is the region containing plagioliparite and propylite as 



