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rather large individuals. It is lacking altogether at times, even 

 where quartz occurs. Remarkable is, that fresh mica so rarely 

 occurs and that more hornblende or augite is not to be found; 

 it is often difficult to decide from what mineral the chloritic 

 pseudomorphs, often associated with carbonaceous mineral, 

 derive, though biotite seems here to have been the predominant 

 mineral. Calcite of very primary appearance is common in 

 many types, through which they ally themselves with the well- 

 known Swedish calcite-granites. The ground-mass is some- 

 times very compact, but never vitreous ; in fact, it is rather of 

 such a kind that in polarized light it resolves itself into sec- 

 lions which themselves seem to constitute cryptopegmatitic 

 quartz-felspar intergrowths, as is the case with certain of the 

 Swedish porphyries from Elfdalen. 



But in the main these types are not specially noticeable 

 petrographically. They are quartz-porphyries, which, however, 

 in their abundance of alkalies and — among the minerals — 

 biotite, show that they correspond to the basic rocks described 

 below. We find more curious developments especially in strongly 

 differentiated varieties, a few of which may be mentioned here. 



On the one hand, then, we have varieties whose main mass 

 consists of the same type of rock as has just been described. 

 One of them is a splendid, somewhat orthoclasiferous mica- 

 porphyrite, almost the freshest of the varieties I saw. The 

 ground-mass is plainly holocrystalline, with a tendency to pass 

 over into micropegmatite. The porphyritic plagioclase crystals 

 seem to have a moderately basic constitution corresponding 

 roughly to labradorite or andesine. This rock contains a frag- 

 ment of a black porphyritic rock with phenocrysts of quartz, 

 plagioclase, biotite and green chloritized pseudomorphs, which 

 must have originated from pyroxene or hornblende. The ground 

 mass is extremely compact and entirely interspersed with a fine, 

 black powder which, curiously enough, shows a pretty fluidal 

 arrangement. That the rocks are, however, closely related to 



