S. IchiTcaioa — Some Notes on Japanese Minerals. 117 



Figs. 5, are similar to fig. 2, but only fig. shows the 

 original cordierite-substance (nat. size). 



Fig. 7 shows transverse and longitudinal sections of a pinite 

 crystal. The outer part of each changed into mica, the wedge- 

 shaped pieces look as if rounded or hollowed ; parallel lines in 

 each piece are cleavage fissure changed into mica (nat. size). 

 Figs. 8 to 12 are the same as fig. 7, but the funnel-shaped 

 portion in fig. S is more micaceous than the adjoining portions, 

 and those in fig. 11 is opposite to the former (nat. size). 



Fig. 13 is a model figure showing the natural composition of 

 the trillings, separated into eight parts by weathering (mag- 

 nified 2 - 5 times). 



Figs. 14 to 10 show parts of the trilling separated by 

 weathering, each piece consists of cordierite and the outer 

 parts are somewhat changed into mica (nat. size). 



Fig. 17 shows the weathering of a pinite, the radial mesen- 

 teries in the center seem to be the secondary sediment of 

 silica which filled the fissures of the trilling and cleavage of 

 the crystal (magnified 3 times). 



In the above study, it is proved that the trillings in the 

 cordierite crystals and the pseudomorphs are separated into 

 eight parts by weathering, and also that each portion of the 

 trillings is gradually changed into mica from the outside and 

 their cleavage-fissures by weathering, till finally a completely 

 micaceous pseudomorph results. The funnel-shaped pieces in 

 the trillings are more rapidly separated or decomposed than 

 the adjoining parts. In the entire micaceous pseudomorph, its 

 cleavage is found in the direction of the basal face as mica, and it 

 is easily cleaved by the finger-nail. The micaceous pseudo- 

 morphs are decomposed into earth at last. 



IV. On the Crystal- Aggregates of Native Arsenic. 



Native arsenic crystals from the Akadani mine, Shimoadiini- 

 mura, Ono-gun, Prov. Fchizen, have been long known by the 

 name of " konpetoishi " ; they occur in association with stib- 

 nite, realgar and minute crystals of pyrite ; the country rock is 

 a liparite. The mineral was first observed by N. Sasamoto,* 

 who also sent specimens abroad, where they have been ex- 

 amined and in part described. Since 1900 I have repeatedly 

 visited Akadani and collected some interesting specimens show- 

 ing the crystal-aggregates. A preliminary note has already 

 been published ;f the following gives fuller details. The varie- 

 ties noted are : 



* Join-. Geol. Soe. Tokyo, vol. ii, p, 461, 1895 ; see also two notes by T. 

 Hiki, ibid., vol. v, pp. 78 and 167, 1898, and vol. vii. p. 363, 1900 ; Mr. 

 Wada's " Minerals of Japan," p. 26, 1904 ; Naumann-Zirkel's " Elemente der 

 Mineralogie," p. 414, 1907. 



f Jour. Geol. Soc, Tokyo, vol. xvi, p. 197, 1909. 



