ox THE SO-CALLED CRYSTALLINE SCHISTS 01" CHICHIBU. 131 



lower one consists of whitish-gray, iionnal sericite-schist, rich in 

 quartz and seririte with the fliara'-teristic riitilr and cal'-ite. At the 

 junction of the Lower and Middle di\isions a very uni<jUe pied- 

 montite-schistO makes its appearance, alternatinii" with the spotted 

 black and green schists ; the two hitter afterwards become the pre- 

 dominant rocks of the Middle division. They are the chlorite-amphi- 

 bolite with white specks of felspars, and the graphite-sericite-scliist 

 with black spots of felspars, these two attaining the great thickness of 

 '200 m. or -/^ of the whole thickness. The characteristic accessory 

 components are tourmaline and calcite. The [pper Sambagawan 

 consists of a phity or paper}' epidote-sericite-gneiss rich in felspar, 

 with the never-failing accessory of epidote. 



The peculiarities of the Sambagawan rocks are the complete 

 absence of the true moscovite or biotite, the abundance of sericite, the 

 want of the microperthitic structure, the presence of tourmaline and 

 piedmontite. Xo trace of organic remains has e^ er been detected. 

 Anyhow, these rocks do not present many of the characteristics so 

 common to the true crystalline schists. 



The question now arises as to the real origin of these rocks. It 

 is not altogether safe for an inexperienced student like the writer 

 to advance any view concerning a probable mode of the formation 

 of such rocks as sericite-gneiss, etc., especially in the face of high 

 authorities in Europe. Still the practical lessons learned bv per- 

 sonal observation in the field, have forced him utter to his views on 

 the genesis of the Sambagawan rocks, whose nearest relatives are to 



1) This is for the first time we fiud the piedmoutite occuniug ia sucli a hirge quautitj' as to 

 eutitle it to the rank of an essential iugredieut of certain rocks. The nearest relative (thnlite) 

 of this mineral is said to have been found iu an eleolite-syeuite from the Serra dos Posços de 

 Caldas in Minas Geraes, in Brazil. Its occurrence seemed, however, at first so strange that 

 Roseubusch was very much astonished on hearing, from Orville A. Derby, of its presence iu 

 the syenite, as may be conjectured by his affixing the sign of interrogation to red epidote or 

 thnlite. " Massige Gesteine " "ite Aufl. p. 90. 



