Ic/rikawa — Etched Figures of Japanese Quartz. 455 



Art. XXVIII. — Studies on the Etched Figures of Japanese 

 Quartz ; by Shimmatsu Ichikawa. With Plates II to VII. 



Introduction. 



In 1910 I published in Japanese a paper with the title 

 " Studies on the etched figures of Japanese Quartz." The 

 present article may be regarded as an abridged translation of 

 that work, with only slight changes. My memoir gives an 

 outline of the studies carried on by me during the four years 

 1905 to 1908. These studies are being continued and a second 

 report with further details will be published later. I am 

 desirous of receiving any suggestions or criticisms from those 

 who may read this paper in regard to any of the points dis- 

 cussed in it. 



1. Artificial Etching of Japanese Quartz (with Plate II). 



The artificial etching of quartz crystals by hydrofluoric acid 

 has already been described by Dr. G. MolengraafI ;* the trans- 

 formations of the original form of the crystal, however, have 

 not yet been discussed in detail. In 1910 I made similar ex- 

 periments on Japanese rock crystal and observed an interesting 

 new form of elevations {Aetz-hugel) produced by etching, and 

 a few new varieties of pits or depressions (Aetz-grubchen). 

 The results of this study are illustrated in the accompanying 

 plate (Plate II). 



Plate II (Concentration of hydrofluoric acid, 55 per cent). 



The grooves on the edges formed by etching can be barely 

 observed by the naked eye, and the pits on the faces can only 

 be investigated minutely under a magnification of 75 to 140 

 times. 



Fig. 1, A, shows etched figures on a left-handed rock crystal 

 from Takemori, Kai Province ; the double lines on the edges 

 indicate the grooves produced by etching. B shows the figures 



on th 



e faces si - — ) , xl ) and mR, etc.; the pits on mR 



much resemble those formed by the combination of the two sets 

 on R and oo K. C is a horizontal projection on the vertical 

 axis of Hg. A ; the dotted lines are the edges as seen from the 

 opposite pole. D shows the form remaining after the crystal of 

 fig. 1, A, had been etched for seven weeks, the dotted hexagon 

 giving the position of the axes ; the form much resembles the 



*Zs. Kr., xiv, 173, 1888, etc. 



Am. Jour. Sci.— Fourth Series, Vol. XXXIX, No. 232.— April, 1915. 

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