COPPER    DEPOSITS    NEAR    LURAY,   VA.  143 
and  has  perhaps  been  dissolved  and  redeposited  many  times  before  finding  its  present  posi- 
tion. Although  ascending  waters  may  have  been  instrumental  in  bringing  up  a  portion  of 
the  sulphides,  such  as  the  chalcopyrite  in  the  quartz  veins  associated  with  the  shear  zones, 
there  is  no  evidence  that  this  sulphide  will  increase  in  depth  or  that  it  occurs  in  large 
bodies.  If  this  concentration  by  descending  surf  ace  waters  be  the  true  origin  of  the  work- 
able bodies,  the  ore  must  be  sought  near  the  surface  and  will  tend  to  diminish  in  depth, 
a  conclusion  in  accord  with  field  observations  at  the  localities  studied. 
Finally,  it  may  be  mentioned  that  these  occurrences  are  examples  of    the  "Catoctin" 
type  of  copper  deposits  of  the  southern  United  States,  which  have  been  described  by  Weed.a 
a  Trans.  Am.  Inst.  Min.  Eng.,  vol.  30,  1900,  pp.  498-504. 
Bull.  285—06 10 
