NO. 14.] MINERALOGICAL COMPOSITION OF THE SAMPLES. 37 



1. Particles of more than 5 mm. 

 No. 1. L63 per cent. Largest grain 1*5 mm., quartz. 

 Almost exclusively quartz in rounded particles; a few grains of felspar, 

 magnetite, biotite, and a single grain of muscovite. 



No. 3 a. 7'74 per cent. Largest grain 1"4 mm., quartz. 



A great majority of quartz-grains, which were found in very large num- 

 bers, most of them only a little larger than 0.5 mm. Some felspar and 

 magnetite were also found, and a few grains of garnet, olivine, and hornblende. 



No. 6. 4'99 per cent. Largest grain 2"5 mm., fine-grained, grey, quartz- 

 itic sandstone. 



Quartz predominated in the remainder, but there were also a great many 

 concretions of iron, consisting for the most part of sandstone, cemented to- 

 gether with limonite; and there were also some clay concretions. Further, 

 there were found a few grains of felspar, magnetite, augite, chlorite, and 

 biotite. 



No. 7. 3*74 per cent. Largest grain 2*2 mm., quartz. 



Quartz predominated, but here, too, there were a number of iron con- 

 cretions. A number of small fragments of quartziferous, fine-grained rocks 

 were also found, which could not be very accurately distinguished from one 

 another, possibly quartzite, quartz-porphyry, granulite, or something similar; 

 also a few grains of felspar and magnetite. 



No. 9. 1"96 per cent. Largest grain 1'2 mm., graphite. 



The remainder was almost exclusively grains of quartz, with a few par- 

 ticles of felspar, magnetite, and similar fine-grained rocks as in the preceed- 

 ing sample, a single piece of sandstone. 



No. 14. 025 per cent. Largest grain 0"7 mm., concretion. 

 The only things found in this sample were 19 brown or black iron con- 

 retions, 9 grains of quartz, and 1 piece of graphite. 



As will be seen from the above, these coarser particles reveal, on the 

 whole, very little as to the nature of the rocks that have yielded material to 

 the bottom-samples. The proportion between the various minerals may indeed 



