HESS    AND 
GRATON. 
OCCURRENCE    AND    DISTRIBUTION    OF    TIN.  177 
Ireland. — Tin  lias  been  found  in  small  amounts  in  several  places  in 
Ireland  under  conditions  much  similar  to  those  in  Cornwall,  but  so 
far  no  workable  deposits  have  been  discovered,  although  a  small 
amount  of  tin  may  have  been  extracted  in  early  times.  The  known 
occurrences  are  at  Dalkey,  county  Dublin,  and  in  Goldmine  Valley, 
county  Wicklow.  Tin  is  also  reported  from  near  the  Lakes  of  Kil- 
larney,  county  Kerry. 
France. — Tin  is  found  in  Brittany,  in  the  western  part  of  France, 
and  in  Creuse,  in  the  central  part,  and  in  a  few  other  places.  A 
small  amount  has  been  produced. 
The  geology  of  Brittany  is  very  similar  to  that  of  Cornwall. 
Granite  is  thrust  through  clay  slate,  and  dikes  of  quartz-porphyry 
and  serpentine  tra Averse  the  country.  Cassiterite  occurs  in  quartz 
veins  in  the  granite  and  in  thin  quartz  veins  and  concretionary  masses 
in  the  schistose  or  gneissic  rocks  between  the  granite  and  slate. 
Topaz,  emerald,  and  arsenopyrite  occur  in  the  veins  with  the  cas- 
siterite. In  Creuse  fluorite,  wolframite,  niobates,  uranium-phosphate, 
calcium-phosphate,  molybdenite,  arsenopyrite,  iron  arsenate,  native 
copper,  melaconite,  and  barite  occur  with  the  tin. 
The  production  in  1902  was  36  tons,  and  in  1903  2?>  tons,  of  tin  ore. 
Spain. — Tin  is  found  in  the  provinces  of  Salamanca,  Zamora, 
Orense,  Pontevedra,  and  La  Coruria  in  the  west  and  northwest,  and 
small  amounts  have  been  found  in  Almeria  and  at  Cartagena  in  the 
southeastern  part. 
In  Salamanca  cassiterite  occurs  in  quartz  veins  cutting  gneiss  and 
Silurian  slate,  with  tourmaline,  wolframite,  some  arsenopyrite,  and 
copper  sulphide  as  accompanying  minerals. 
In  Zamora  cassiterite  occurs  in  quartz  veins  cutting  granite  and 
crystalline  schists  at  their  contact.  Besides  cassiterite  the  veins  also 
carry  much  tourmaline  and  some  fluorite,  apatite,  white  mica,  molyb- 
denite, chaleopyrite,  sphalerite,  and  galena.  The  arsenopyrite  is 
sometimes  argentiferous.  White  mica  occasionally  penetrates  the 
cassiterite. 
The  occurences  in  other  provinces  are  similar. 
Alluvial  deposits  sometimes  carrying  gold  occur  in  the  vicinity  of 
the  veins,  and  a  small  amount  of  mining  has  been  done  since  the  time 
of  Pliny. 
The  output  for  1901  was  126  tons  of  dressed  ore.  In  1902  the 
output  was  11  tons. 
Portugal. — Tin  is  found  in  the  provinces  of  Beira,  Minho,  and 
Tras-os-Montes,  where  it  is  found  as  stockworks  in  the  granite,  veins 
in  the  older  slates,  and  in  alluvial  gravels  in  the  vicinity  of  these 
deposits.  The  geology  is  much  the  same  as  in  the  neighboring 
Spanish  provinces. 
Bull.  260—05  m 12 
