EAUT11(,>UAKE OF CEXTKAL JAPAX, 1891. ^H 



and of lionibleude, biotite, and (juartz. The honiblonde, appearing macroscopically 

 as a porpliyritic ingredient, is really an accumulation of amphibole and biotite, and 

 these decidedly belong to the second generation of crystals. The irregular plates of 

 hornblende, deeply indented by grains of (j[uartz, and interlarded throughout by 

 prisms of apatite, arc of a deep bluish-green colour and pleochroic. The brown 

 librous biotite has usually grown with amphibole into irregular tufts, and with them 

 clumps and crystals of magnetite are commonly found. In one slide examined 

 botli magnesinm-bisilieates arc greatly decomposed into a green übrous mass, finally 

 changing into a chloritic substance. In this case a large quantity of dust and 

 numerous crystals of magnetite, together with leucoxene, have settled within the 

 confused aggregates, accompanied by secondary epidote. 



The feldspar of the general mass is not striped, and is much more decomposed 

 than the phenocryst. Its form is imperfect, being conditioned by the mutual 

 disposition of the same species and of the magnesium-bisilicates. The quarts is 

 present only in small quantity, and is irregular in its form, having filled up the 

 interstitial spaces left by other ingredients. It is of course fresh, displaying the 

 usual vivid chromatic polarization, while the other components are more or less 

 decomposed, and conse(j^uently appear dull. Well-finished crystals of it arc nowhere 

 observed. It is interesting to note that the quartz contains abundance of liquid and 

 gas-inclusions, the former often holding dancing bubbles and also s)iitdl viihes, prohahbj 

 of soiliiiiit-cliluride. Glass-inclosures are so far not observed. 



Zircon is found in the combination of I* and x V, and titanitc is found in 

 irregular grains. Apatite is plentiful ; its cross-sections are licxaijons irith allenudchj 

 tniiicdU'd canu'is, the longitudinal sections being lath-shaped exactly like those of a 

 tourmaline. Neither the transverse nor the longitudinal section of the apatite 

 becomes totally dark in any position during complete rotation upon the stage. Its 

 crystals contain, especially in their central portion, a large number of gas and li(juid- 

 inclusions with spontaneously moving bubbles. 



Another slide, made of a specimen from the same locality, presents characters 

 somewhat deviating from the above, in respect to structure, the general mass being 

 for the greater part made up of an intimate intergrowth of quartz and feldspar in 

 // 1(1 (jrec form. The general aspect of our granite-porphyry seems to have a close 

 resemblance to the rock, called by v. lUchthofen,"' the Corean granite, from Kauli- 



* "Cliinu." Off. 11. «chwerdt, rittersuchunn über Gesteine der cluwj^^isdwn rrocin.cii Scliaii- 

 tuiiij und Hnntuiiij. Zi-itacUr. d. d. geol. Clesell. Btl. 38, p. 211. 



