& IcJiikawa — Some Notes on Japanese Minerals. 115 



Fig. 7 shows rhombohedral elevations formed on a face oo R 

 of a short prismatic crystal more etched than fig. 1, A (magni- 

 fied 70 times). 



The symmetry of the etched figures on the above crystal 

 faces corresponds to the symmetry of the group to which the 

 given crystal belongs, and the form resulting from the etching 

 is supposed to be a rhombohedron (see fig. 1, B ; fig. 7, etc.). 



For Meyer's results on calcite crystals see Jahrb. Min. I, 74, 

 1SS3 ; and for those of Lavizzari on a calcite ball etched with 

 sulphuric acid see Naumann-Zirkel's Elemente der Mineralogie, 

 p. 200, 1907. 



The results of K. Jimbo on the natural etching of calcite 

 crystals from Kitahama, Izumo Province, are described in 

 Jour. G-eogr. Tokyo, vol. vii. 226, 1899. Also those of F. 

 Otsuki on the natural etching of calcite crystals from Sawada- 

 mura, Kamo-gun. Izu Province, in the same journal, vol. viii, 

 283, 1900. 



III. Finite : A Mica Pseudomorph after Cordierite in Trillings 

 from Ibrihama. 



The trillings of Japanese cordierite crystals and their pseudo- 

 morphs have already been described by Prof. A. Kikuchi,* B. 

 Koto,f K. Jimbo,;}: Mr. S. Hirose,§ and others. In these 

 papers, however, the structures of the trillings in the crystals 

 and their pseudomorphs have not yet been discussed in detail. 

 In 1908 I personally visited Torihama, Ya-Mura, Mikata-gun, 

 Wakasa Province, which has been long known as a locality of 

 pinite, and collected a few weathered specimens of the mineral. 

 The results of the study of these specimens are mentioned in 

 the accompanying figures (III). 



Fig. 1 is an individual of the pinite (natural size). A, shows 

 a part changed into mica. 



Fig. 2 shows the structure of the trilling in a section plate 

 cut perpendicularly to the vertical axis of the pinite. The 

 black portion shows the original substance of the cordierite ; 

 the remainder is the pseudomorpbous mica ; parallel lines show 

 cleavage fissures changed into mica (magnified 2 times). 



Figs. 3-4 show the structure of the trillings in basal sections ; 

 the specimens are wholly changed to mica. The white part 

 in the figure shows micaceous substance, and the rest is an 

 earthy substance produced by the decomposition of the mica 

 (nat. size). 



* Cordierite from Watarasegawa, Jour. Sci. Coll., vol. iii, 1890. 

 + Cordierite from Doshi, Jour. Geogr. Tokyo, vol. xvi, 224, 1909. 

 X Cordierite pseudomorphs from Tsukuba, Torihama, Doshi, etc., Beit. 

 Min. Japan, II, 62, 1906. 

 § Cordierite from Sakuratenjin, Jour. Geogr. Tokyo, vol. xxi, 66, 1904. 



