COPPER  DEPOSITS  NEAR  LURAY,  VA. 
By  William  Clifton  Phalen. 
INTRODUCTION. 
: 
In  an  investigation  of  the  copper  deposits  of  the  eastern  United  States  by  Mr.  W.  H 
Weed,  the  writer  was  detailed  to  reexamine  several  properties  in  the  Blue  Ridge  regio 
near  Luray,  Va.  The  special  object  of  this  work  was  to  find  additional  evidence  con- 
cerning the  genesis  of  the  ores,  previous  examinations  by  Mr.  Weed  having  resulted  in 
conclusions  wholly  at  variance  with  the  opinions  held  by  the  various  companies  operating  in 
the  region.  This  paper  is  based  on  field  observations  and  careful  study  of  thin  sections 
under  the  microscope. 
Location. — The  region  treated  in  the  following  notes  lies  at  or  near  the  summit  of  the 
Blue  Ridge,  between  Page  and  Madison  counties,  Ya.,  and  along  the  western  foothills  of 
the  same  a  few  miles  south  of  Luray,  also  near  the,  crest  of  the  ridge  near  High  Knob, 
between  Greene  and  Rockingham  counties,  some  distance  to  the  southwest. 
THE  ROCKS. 
In  general,  the  Blue  Ridge  in  this  section  is  made  up  chiefly  of  basalt,  but  along  its  west- 
ern flank  at  various  points  may  be  seen  the  outcrop  of  an  extensive  mass  of  syenite.  On 
I  he  east  flank  of  the  ridge,  near  the  head  of  Robertson  River  (Robinson  Rivera)  and  a 
few  miles  southeast  of  Fishers  ( rap  I  Milams  Gap  «),  in  Madison  County,  there  is  an  intrusion 
of  biotite-granite.  Of  these  rocks  the  basalt  has  the  more  interest  in  this  connection  from 
the  fact  that  it  carries  the  copper  ore.  It  is  inferred  that  this  rock  is  the  Catoctin  schist 
of  Keith, 6  and  that  it  is  coextensive  with  the  South  Mountain  basalts  of  Pennsylvania! 
described  by  Bascom  c  and  Williams/*     According  to  Keith,  the  rock  is  Algonkian  in  age. 
The  chief  mass  of  the  basalt,  or  melaphyre,  or  greenstone,  as  it  has  been  variously  termed, 
is  dense  and  dark  green,  except  where  thoroughly  epidotized,  when  it  assumes  a  lighter- 
green  hue.  Its  original  constituents  are  not  determinable  without  microscopic  aid,  save  per- 
haps an  occasional  phenocryst  of  olivine.  From  the  facts  that  bosses  of  syenite  are  seen 
in  it  in  the  region  near  Fishers  Gap  and  that  it  has  been  subjected  to  an  intense  metamoa 
phism  along  its  contact  with  the  syenite  on  the  west  slope  of  the  ridge  and  wherever  the 
two  rocks  are  contiguous,  it  is  inferred  that  the  syenite  is  the  younger  of  the  two  rocks. 
This  inference  is  strengthened  by  the  perfectly  fresh,  noncrystalline  character  of  the 
syenite  at  the  immediate  contact  and  by  the  lack  of  weathered  fragments  or  bowlders  of 
the  syenits  in  the  basalt.  This  contact  metamorphism  has  resulted  in  a  more  or  less  schistose 
rock,  quits  different  from  that  of  the  main  mass,  which,  in  this  particular  district,  is  not 
regionally  schistose.  The  basalt  is  regarded  as  more  recent  than  the  granite  of  "the  east 
side,  from  the  metamorphism  exhibited  by  the  latter  along  the  contact.  This  has  resulted 
in  a  gneissoid  belt  several  feel  in  width.  These  conclusions  regarding  the  relative  ages  of 
the  igneous  rocks  have  been  deduced  from  the  examination  of  a  limited  number  of  contacts 
«  Names  in  parentheses  are  used  locally. 
b  Keith,  A.,  Fourteenth  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  2,  1894,  pp.  296  et  seq. 
c  Bascom,  F.,  Bull.  U.  S.  Geol.  Survey  No.  136,  1896,  pp.  68  et  seq. 
d  Williams,  G.  H.,  Am.  Jour.  Sci.,  3d  ser.,  vol.  44,  pp.  490-496. 
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