472 Ichikawa — JEtched Figures of Japanese Quartz. 



APPENDIX. 

 Quartz Work in Japan. 



In 1906, I personally visited the quartz works at Kofu, Kai 

 Prov. ; since then, in 1909, I visited the quartz and agate- 

 works at Onu, Wakasa Prov., and the amethyst and jasper- 

 works at Matsue, Izumo Prov., and obtained some interesting 

 knowledge of quartz- work. I give below a summary of the 

 results : 



The cleavage of quartz crystal is not distinctly observed, but 

 it is proved by etching that the fracture surfaces are sometimes 



parallel with i?, — - — , , oo i?, etc. ; besides this cleavage 



is also imperfect parallel with oo _P2, or the direction of the 

 intermediate axes. This was proved by the experience of a 

 sculptor at Kofu, many years ago ; it is found that a crystal can 

 easily be cleaved in two if a shallow groove be dug perpen- 

 dicular to the oscillatory combination of the prismatic face 

 and struck lightly with a wedge. In this case it emits a 

 stronger phosphorescence (triboluminescence) than when it is 

 cleaved in other directions. 



The fracture of quartz crystal is conchoid al or subconchoidal, 

 but the fracture perpendicular to the vertical axis of the crystal 

 is more regularly conchoidal than in other directions. In 

 quartz-work, the needless parts of the original quartz are 

 broken away with a little hammer and a slender chopstick of 

 steel ; in this way, a skillful sculptor dexterously makes up the 

 outlines of a sphere, seal or paper-weight, etc., with many 

 conchoidal fractures perpendicular to the vertical axis of the 

 original crystal, the direction in which cleavage is not found, 

 and then these surfaces are polished by emery. In the produc- 

 tion of tigers, lions, personages, etc., the needless parts of the 

 original quartz are cut away with a wire of steel and emery. 



The hardness of quartz crystal is 7. but it is not the same on all 

 faces of the crystal, the prismatic faces are harder than others 

 and the artificial basal section is much softer than the natural 

 crystal faces. This is proved by the etching and polishing; 

 therefore letters of quartz-seals in Japan are carved on the 

 artificial basal section of the crystal. 



Primary quartz is more brittle than secondary quartz, as 

 shown by the fact that the sculptors of Kofu distinguish be- 

 tween the brittleness of rock crystal from the pegmatite of 

 granite from Kinbuzan, and rock crystal from quartz vein of 

 spotted clay slate formed by contact with granite from 

 Takemori.* 



* See my note ' ' On the luster and brittleness of rock crystal " in Jour. Geogr. 

 Tokyo, vol. xvi, 541, 1909. 



