178  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull.  225. 
productive,  have  been  found  in  the  same  region.  A  partial  analysis 
by  Dr.  E.  T.  Allen  of  an  average  sample  of  the  chromite  selected  in 
the  mine  gave  the  following  results: 
Partial  analysis  of  chromite  from  Shot  Gun  Creek. 
Per  cent. 
Cr203 - 43.87 
FeO  (total  iron  reckoned  as  FeO) 15.  86 
Platinum,  gold,  and  silver None. 
The  ore  is  used  for  furnace  linings,  and  315  tons  were  shipped  in 
1902. 
IRON   ORE. 
The  iron-ore  deposits  of  the  Redding  quadrangle  were  noted  in  Bul- 
letin 213,  page  219,  but  since  then  other  observations  have  been  made 
and  one  of  the  localities  prospected,  although  no  ore  has  been  removed 
except  that  formerly  used  for  flux  at  Bully  Hill.  It  occurs  at  two 
points  in  quantities  worth  noting.  The  first  is  1\  miles  southeast  of 
Baird,  and  the  second  on  the  northeast  slope  of  Hirz  Mountain,  near 
the  McCloud.  The  ore  in  both  cases  is  chiefly  magnetite,  changed  to 
limonite  at  the  surface,  and  occurring  on  the  contact  between  the 
McCloud  limestone  and  a  dioritic,  often  diabasic,  rock  which  cats  it. 
At  the  first  locality  the  occasional  presence  of  small  bands  of  garnet 
and  traces  of  other  related  minerals  locally  in  the  magnetite  indicate 
that  it  is  a  contact  phenomenon  similar  to  that  in  the  Black  Diamond 
region.  The  ore  body  has  been  opened  to  a  width  of  40  feet  without 
exposing  its  limits.  It  appears  to  be  nearly  vertical,  and  its  occurrence 
on  the  north  slope  of  the  hill  suggests  an  ore  body  of  considerable 
size.  As  to  its  composition,  Mr.  Keating  informs  me  that  it  contains 
about  70  per  cent  of  iron,  1  or  2  per  cent  of  insoluble  material,  and 
only  a  trace  of  sulphur. 
On  the  northeast  slope  of  Hirz  Mountain  the  iron  ore  has  a  somewhat 
wider  distribution,  but  this  may  be  due  to  the  gentle  dip  to  the  east 
parallel  to  the  slope  of  the  limestone.  It  has  been  prospected  by  a 
number  of  open  cuts,  and,  as  in  the  other  case,  is  generally  a  contact 
deposit  on  the  borders  of  the  limestone  and  diorite,  but  in  places 
appears  to  penetrate  the  diorite. 
In  both  cases  the  bodies  of  magnetic  iron  ore  are  large,  but  the 
contacts  are  very  irregular.  Each  contains  an  element  of  promise 
of  other  ore  bodies  below,  for  at  the  Black  Diamond  mine  both 
chalcop}^rite  and  pyrrhotite  are  common  with  the  magnetite. 
CLAY. 
Clays  of  two  sorts,  occurring  under  entirely  unlike  conditions,  have 
been  used  in  the  Redding  quadrangle.  In  the  copper  region  clay 
selvage  to  the  ore  bodies  is  never  very  abundant,  but  in  some  of  the 
upper  workings  of  the  Bully  Hill  mine  there  is  enough  for  local 
use  to  line  the  converters  in  the  smelter. 
