NOTES ON THE MINERALS OF JAPAN. 249 



The colour of topaz from Mino are bluish or brownish to 

 quite colourless. Pleochroism is sometimes distinct. 



As in the crystals from Tanokamiyama, we often find a 

 peculiar division of individuals into differently coloured sections, 

 being light brownish on the ends of the a axis and light bluish 

 on those of the b axis. The topaz crystals from Mino are from 

 0.2 cm. to 12.5 cm. in the longer diameter of basal sections. 

 Enclosures in this mineral consist of tourmaline, cassiterite, chlo- 

 rite (?), liquid, gas, &c. Crystal faces usually observed are : 

 oP, 2P00, 4P 00, 2PCÔ, P, 2P, cop^ and coPt. Besides these, are 

 less frequently observed : co P^, œ Pf, od P|, go P|, go P|, goP|, 

 c^P^, |P^, IP, |Pä5, 4PT, 2P¥, IPir, fPT, fP, tP, &c. The 

 last mentioned three faces were found by Redlich (Tschermak's 

 Mittheilungen 1897). 



The following natural etching figures of Mino crystals are 

 mentioned in Hiki's work : — 



On oP (c), numerous rectangular pyramids. 



On iVcß (f), triangular eminences, with their base paral- 

 lel to the a axis, with apex directed towards the adjacent face 

 of oP, and with two other sides parallel to the edges of combi- 

 nation of 00 P2' and 2P 00. 



On 2P (0), triangular and other eminences. 



On P, (u), irregular horizontal striae. 



On CO p (m), quadrilateral eminences. 

 Besides there are less important figures on various faces. 



In the beautiful topaz collection of Wada, which is specially 

 rich in crystal forms, enclosures, etching figures, &c. of the 

 Japanese specimens there are to be seen many other characteris- 

 tic etching figures. For instance, in one nearly colourless crystal 

 from Mino measuring about 2 cm. along the b axis, there are 



