180  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         [bull.  260. 
Suo,  and  Hyuga,  and  fluviatile  deposits  have  been  found  in  Mino 
and  Bungo. 
The  only  production  at  present  is  at  Taniyama,  in  the  province  of 
Satsuma,  where  21  quartzose  veins,  ranging  from  a  few  inches  to  4 
feet  in  thickness,  are  worked.  They  traverse  soft  tuffs  and  Mesozoic 
shales  and  sandstones,  with  occasional  beds  of  dark-blue  quartzite. 
The  surface  is  almost  everywhere  covered  with  modern  pumice,  and 
exposures  of  volcanic  rocks  are  common. 
The  cassiterite  grains  in  the  veins  are  of  almost  microscopic  size. 
The  ore  runs  from  10  to  13  per  cent  tin  in  places,  and  is  accompanied 
by  galena,  pyrite,  pyrrhotite,  and  sphalerite  of  secondary  formation. 
At  Suzogoya,  Hitachi  province,  tin  occurs  in  quartz  veins  cutting 
Paleozoic  sandstone,  with  dark-brown  mica,  magnetite,  pyrite,  and 
galena. 
At  Takayama  and  other  places  in  Mino  province  cassiterite  occurs 
with  quartz,  tourmaline,  topaz,  wolframite,  beryl,  sapphire,  fergu- 
sonite,  and  naegite,  a  new  silicate  of  uranium  and  thorium. 
At  Kiwada,  Suo  Province,  cassiterite  is  found  in  veins  cutting 
metamorphosed  Paleozoic  clay  slate.  The  vein  stone  consists  of 
quartz  with  fluorite,  scheelite,  magnetite,  chalcopyrite,  sphalerite, 
garnet,  pyroxene,  and  calcite. 
At  Iwato,  Hyuga  Province,  cassiterite  occurs  with  limonite. 
Tin  has  been  mined  in  Japan  since  the  seventh  century,  but  most 
of  the  mines  are  now  exhausted.  In  1901  the  output  was  about  15.5 
tons  of  tin. 
MEXICO. 
Tin  has  been  found  in  a  large  number  of  places  in  Mexico  over  a 
considerable  scope  of  country.  It  occurs  in  the  States  of  Zacatecas, 
Jalisco,  Guanajuato,  San  Luis  Potosi,  Sonora,  Durango,  and  Lower 
California. 
In  general  the  geology  of  the  different  localities  is  much  the  same. 
The  country  rock  is  rhyolite  and  rhyolite  tuff,  of  Tertiary  age, 
generally  associated  with  a  fine-grained  granite,  but  sometimes  with 
thin-bedded  Cretaceous  shales  and  limestones,  as  at  Sain  Alto,  Zaca- 
tecas. Cassiterite  occurs  along  joint  planes  in  pockets,  bands,  and 
impregnations,  often  in  mamillary  or  botryoidal  concretions,  forming 
the  so-called  "  wood  tin,"  often  beautifully  colored  red,  yellow, 
brown,  black,  and  other  colors. 
The  accompanying  minerals  are  quartz,  fluorite,  topaz,  durangite, 
manganese  minerals,  biotite,  hematite,  and  chalcedony. 
At  Sain  Alto  there  is  a  small  output  of  1  to  3  tons  of  tin  eacfl 
year,  which  is  used  locally.  The  ranchers  collect  fragments  of  ore 
from  cracks  in  the  bed  rock  of  the  mountain  streams  after  the  winter 
