Yol.  49.] 
GOLD-QUARTZ  DEPOSITS  OF  PAHANG. 
87 
quartz-lodes,  that  most  of  that  alluvial  gold  is  derived  which  is  now 
found  in  the  gravel  of  so  many  river-beds  and  valleys  in  the  Malay 
Peninsula. 
The  peculiar  formation  of  the  famous  Paub  Hole  may  be  con¬ 
sidered  as  intermediate  between  the  two  classes  of  deposits,  for 
though  each  vein  may  be  regarded  as  a  separate  lode,  yet  within  a 
certain  zone  the  whole  series  of  the  black  slate-rock  which  contains 
the  veins  is  distinctly  ‘mineralized,’  being  highly  charged  with  iron 
pyrites,  and  thus  a  more  or  less  definite  rock-zone  is  constituted, 
which  may  be  considered  as  one  great  ore-deposit. 
2.  Irregular  Formations. 
I  pass  now  to  a  description  of  the  second  form  of  deposits. 
Many  quartz-lodes,  and  even  some  of  those  which  appear  most 
regular  in  portions  of  their  course,  are  intimately  associated  with 
dykes  or  intrusions  of  igneous  rock  which  traverse  the  sedimentary 
strata  of  Pahang,  and  constitute  an  important  element  in  the 
geological  formations  of  that  country  ;  it  seems  even  probable  that 
the  whole  auriferous  occurrence  is  induced  by,  or  is  in  some  way 
consequent  on,  this  igneous  agency,  though  its  connexion  is  distinctly 
evident  in  some  places  only  and  has  not  yet  been  traced  in  others. 
These  dykes  consist  of  several  varieties  of  highly  felspathic  rock, 
which  (though  they  have  not  hitherto  been  critically  examined)  may 
be  called  trachyte-porphyries. 
Where  prominently  associated  with  auriferous  quartz,  these  dykes 
are  generally  found  to  be  in  a  state  of  decomposition,  rendering 
their  substance  (which  has  become  chiefly  kaolin)  soft  and  disinte¬ 
grating,  from  the  surface  down  to  the  limited  depths  as  yet  reached 
in  the  mines.  Their  junction  with  the  sedimentary  rocks  is 
sometimes  sharply  defined,  and  often  marked  by  a  strong  inter¬ 
vening  contact-vein  of  quartz.  At  others  the  juncture  is  irregular, 
branches  of  the  dyke  penetrating  the  strata  or  confusedly  mixing  with 
the  latter,  which  are  consequently  contorted  and  metamorphosed. 
Auriferous  quartz-veins  traverse  these  dykes  besides  following  their 
junction  with  the  sedimentary  rock,  sometimes  in  large  lodes  and 
sometimes  in  numerous  minor  strings  and  parallel  veins,  the  general 
strike  of  which  seems  to  coincide  with  that  of  the  dyke,  though  often 
they  follow  several  contrary  and  intersecting  courses. 
These  d}^kes  may  then  be  regarded  as  another  form  of  deposit  of 
the  stockwork  type,  in  many  respects  resembling  those  in  the  slates 
with  which  they  are  sometimes  in  juxtaposition  or  intimately 
associated. 
Much  of  the  gold  in  the  alluvial  deposits  of  Pahang  must  have  been 
derived  from  these  dyke-quartz  formations,  the  tendency  of  which 
is  to  decompose  rapidly,  in  respect  of  their  felspathic  matrix.  Owing, 
however,  to  the  harder  skeleton  of  quartz-veins  which  they  contain, 
their  courses  are  frequently  marked  as  low  hill-ranges,  from  which 
the  soft  slates  have  been  more  rapidly  denuded  into  depressions  on 
either  side.  A  remarkable  result  of  the  process  of  weathering  on 
