GEOLOGY AND ORE DEPOSITS OF SU-AN 21 



Pit No. 23, already referred to, was sunk to prospect the 

 loiver portion of the outcrop. Following the irregularly scattered 

 metallic sulphides in granitic rock, the pit goes down in a round- 

 about way to the heading, the direct distance from the entrance 

 being 30 feet N. N. E. Here iron-pyrite is seen confusedly mixed 

 up with quartz, both occurring in disconnected patches. Such an 

 impregnated portion may associate some minute quantities of gold, 

 as is shown by the analysis of specimen No. 46, taken from this 

 spot. 



There are a number of pits, some are marked in the accom- 

 panying geologic map (PI. IV.), and these are opened in pursuit of 

 comparatively good ores without any fixed direction or fixed level. 



From the careful observations made by Dr. K. Nakashima 

 both in open works and in pits, the probable limit of the ore- 

 yielding area is divided, as has been already stated, into the 

 western and the eastern ore-bodies. The former measures 

 in rough figures 350 feet from N. W. to S. E., as well as from 

 N. E. to S. W., while the latter is about 360 feet long and 60 

 feet wide. If we admit the intervening space of the two ore-bodies 

 to be uniformly ore-bearing, the total length may exceed 800 feet ; 

 but so far as his observation goes, Nakashima was not able to 

 find, along the contact of the hornfels with the porphyritic granite 

 in this intermediate area, any actual evidences of the existence of 

 workable ores. 



Outside the two ore-bodies, outcrops have been searched for 

 in every direction in the vicinity of the Hol-gol mine. To the 

 east of the mine at the sites marked A, B, C, and D on the map 

 (PI. IV.), and also on the north of the mine down the Hol-gol 

 valley at points E and F, we find limestones locally changed 



