S. Ichikawa — Some Notes on Japanese Minerals. 67 



In tbe above study it is proved that the cleavages of gypsum 

 crystals are in the direction of the faces ooP oh^ P^ cc JPao , 

 etc., and the latter are less perfect than the first-named. The 

 flexibility of the crystals is more conspicuous along the face 

 oopoo than in other directions. 



VII. Dendrites of 3fanganese Oxide. 



In 1912 I visited mineral localities in Echizen Province and 

 collected some interesting specimens of manganese oxide in 

 dendritic and circular forms; some of these are illustrated in 

 the accompanying plate (III). 



Fig. 1 (nat. size) shows dendrites formed in the fissure of a 

 Tertiary siliceous sandstone from Yamanokoshi, Kamiyama- 

 mura, Nanjo-gun. The outlines of the dendrites, as is often 

 the case, much resemble natural views with mountains, trees, 

 etc. 



Fig. 2 shows manganese oxide in concentric zonal rings, 

 formed in the fissures of the platy joints of an andesite from 

 Knrashita, Tani, Kitatani-mura, Ono-gun. When fresh the 

 rings are black and yellow, but these colors are gradually 

 bleached on exposure to the air. B and C show a group of 

 concentric zonal rings ; the rings marked a in each figure are 

 yellow and the others black ; h shows plagioclase cj-ystals which 

 form phenocrysts in the rock. A is reduced to one-third ; B 

 and C are natural size. A plate of the dendrites was pre- 

 sented to the Twelfth International Geological Congress in 

 Toronto, Canada, in August, 1913. 



Fig. 3 shows dendrites formed on calcite crystal from Shimo- 

 shinjo, Shinyokoe-mura, Imatate-gun (magnified 10 times). 

 A, front view ; B, a horizontal projection on the vertical axis. 

 The calcite crystal is colorless and transparent, but its surface 

 is somewhat weathered. In the specimens a group of dendritic 

 forms is sometimes changed to yellow. It is shown here that 

 dendrites of manganese oxide, besides the usual forms, form 

 concentric zonal rings, yellow and black, alternately. 



Errata. — The following errata are to be uoted in my papers 

 in this Journal: 



Vol. xxxix, April, 1915, p. 459, footnote: for vol. xvi, p. 197, 

 read vol. xvi, p. 1. — P. 463, second footnote: for Jour. Geogr. 

 Tokyo, read Jour. Geol. Tokyo. — P. 468, second footnote: for 

 vol. iii, No. 13, read vol. iii, No. 12. 



Vol. xlii, August, 1916, p. 115, line 14 from top and also in 

 the second and fourth footnotes: for Jour. Geogr. Tokj'o, read 



