70 T. HIKI. 



rounded, especially in large specimens ; but small crystals with sharp 

 edges are met with not infrequently. The crystals are well defined in 

 those rare cases in which they occur in veins of smoky quartz forming 

 a network in disaggregated granite. Granite seems to have been the 

 mother rock of the topaz and of the minerals found with it in dilu- 

 vium, viz., cassiterite, magnetic iron sand, smoky quartz, tourmaline, 

 beryl, muscovite, biotite, orthoclase, plagioclase, sapphire, gold, pyrites, 

 fluorite, wolframite, fergusonite (?), &c, for these minerals are ap- 

 parently all to be found in quartz veins in the granite. 



Literature. — Crystals of topaz from the provinces of Mino and 

 Omi, 1 were first studied by T. Wada. 2 He mentioned, that they bear 

 some resemblance to those from the Urals and Schneckenstein. The 

 late Assistant- Professor Y. Kikuchi 3 has given a brief account of 

 topaz from Mino, and classified it under three types. A. Hahn 4 has 

 described above two hundred specimens from Mino. W. D. Matthew 5 

 has also described seventy-five crystals from Omi and twenty-five 

 from Mino. Lastly, Penfield and Minor, 6 have written about the 

 chemical and physical characters of the topnz from Mino. 



Y. Kikuchi left his investigation unfinished ; and his collection 

 and mine, (the number of crystals examined being above five hundred) 

 form the subject of the present paper. 



Character of the Crystals. — The crystals are short columnar forms, 

 and vary considerably in dimensions, the width from 0.5 to 10 c. m., 

 and the length from 1.5 to 30 c. in. They are distinctly hemimor- 

 phic, when both ends are developed. Parallel growth of two in- 

 dividuals, is sometimes observed. Most of the crystals are transparent; 



1. Another topaz locality of Japan. 



2. Sitzungsberichte der Gesellschaft Naturwissenschaftlicher Freunde zur Berlin. 1884. 



3. Rigaku-kyokai-Zasshi. 1887. 



4. Groth, Zeitschr. f. Kryst. u. Min. 1893. 



5. Neues Jahrbuch, f. Min. &c. Referate. 1894. 



6. Groth, Zeitschr. f. Kryst. u. Min. 1894 



