NOTES ON THE MINERALS OF JAPAN. 221 



We find also the faces co O and [-^]. Simple octahedra are 

 seldom met with. Striations on O and ccQœ are due to 

 oscillatory combinations of these faces with go O and [^-^J, as 

 in the specimens from Ogasawarajima, Osarnzawa, Ani and Ara- 

 kawa. Striations on f''-^] are mostly parallel to its regular 

 edges, but in rare cases perpendicular to them. Besides there 

 are striations on a)Oœ, running paralled to f-^l-^] and 2O2. 

 Each crystal is developed usually on all sides, for it is found in 

 a clay vein. 



Ogoya. — Pyrite crystals which are here found with copper- 

 pyrite, &c. show O, c^ O o), [-^^], 2O2 and [^]; and have 

 an octahedral habit usually with very subordinate [-^^J» <-^c. 

 The individuals of pyrite attain 2 cm. in diameter. 



ToHTRA in Rikuchü Province. — The specimens of pyrite 

 from Tohira, described by Hiki, show a peculiar rhombohedral 

 habit on account of the development of only six of the dodecahedral 

 faces. The crystal-form is nothing but f-^-J- coOco. The size 

 of individuals is sometimes more than 2 cm. in length. 



Quite a similar form of pyiite is seen at Akadani in Echigo 

 Province, where the largest individual is about 4 cm. in length 

 and the crystal developed on all sides, as at Tohira. 



Good specimens of supplementary twins of dodecahedra 

 were found in Ogasawarajima and at Ani(?). 



The face of |0 was only observed in a specimen from 

 Ohinata in Shinano. 



19. Marcasite. 



Botryoidal aggregates and crystal groups of marcasite were 

 collected in the Aikawa mines in Sado. Small spherical or 



