ON THE SO-CALLED Cr.YSTALLTXE SCHISTS OF CHICHIBU. 12.5 



from various lidiologists, such as (t. H. ITawes,^) K. 1). Ir\ing,^) 

 J. Lehmann,*) Hj. Sjögren,^^ G. H. Williams,^) and many others ; 

 and we are indebted specially to the last author for a detailed account'^) 

 of the paramorphosis of pyroxene to a7n])hibole. 



Most American writers adhere, with good reason, to the \ iew of the 

 secondary nature of not only the green compact, but also the brown 

 basaltic hornblende, which Kloos considers a matter of impossibility 

 (op. cit). My study of Japanese gabbros confirms the view entertained 

 by the American lithologists, and the following short account of the 

 hornblendes may prove not to be entirely wanting in interest. 



Onr rock from Minano contains large ])orphvritic crystals of 

 diaUage which is undergoing paramorphosis. The large core is sur- 

 rounded by a zone of perfectly compact hornblende ; the interior 

 boundary of this rim, i. e., the line of contact between it and the 

 diallage-remains, is the most irregular possible. The most delicate 

 tongues and shreds c)f hornblende extend from the outer rim into the 

 diallage-substance in every direction in a most complicated manner, 

 so that it is impossible either to describe or to portray it adequatelv. 

 The diallage and hornblende, which are well distinguished by differences 

 in colour and optical orientation, are not really separated liv sharp 

 lines of contact. They everywhere shade intc^ one anc^ther bv insensi- 

 ble gradations. The transition of substance is so gradual that it is noi 

 possible to detect the exact points where one l)egins and the other 

 ends, even under the highest power of the microscope. Xowhere does 



2) The Lithology of New Hampshire. Cf. E. D. Irving, (foot-note 3). 



3) On tlie Paramorphic Origin of the Hornblende of tlie Crystalline Eocks of tlie North- 

 western States. Amer. Journ. Science, 1S84. If, XXXVITI, p. IßlJ. 



4) Ueber die Entstehung der altkrystiilliuischeu Schiefergesteine, etc. p. IJIQ. 



;')) Geol. Foren, in Stockholm Förh. Cf. Neue« Jahrb. f. Mineralogie, etc. 1884, I, p. Sl. 



6) Bulletins U. S. Geol. Survey, Vol. 4. The Gabbros and Associated Hornblende Eocks, 

 p. 051. 



7) On the Paramorphosis of Pyioxene to Hornblende in Eocks. Amer. .Tonru. Science, 

 XXVni, 1881, Oct. p. 2r,9. et seq. 



