bichardson.]    NATIVE    SULPHUR    IN    EL    PASO    COUNTY,    TEX.  591 
About  10  miles  northwest  of  Rustler  Spring,  just  east  of  the  Toyah- 
Guadalupe  road,  a  low  gypsum  hill  is  capped  by  20  feet  of  gray  lime- 
stone lying  practically  flat.  Several  hundred  feet  have  been  stripped 
along  the  southern  side  of  the  hill,  exposing  a  good  section.  Amor- 
phous yellow  sulphur  occurs,  disseminated  in  irregular  streaks  and 
patches  in  the  gypsum,  occasionally  rudely  following  the  bedding, 
and  again  crossing  it,  not  following  any  regular  course.  The  sulphur- 
impregnated  zone  averages  about  8  feet  in  width.  The  contact 
between  the  gypsum  and  the  limestone  is  extremely  irregular.  The 
gypsum  and  the  limestone  are  intimately  intermingled  and  porous, 
which  suggests  local  derivation  of  the  gypsum  from  the  limestone 
adjacent  to  the  contact, 
A  test  pit  H  miles  northeast  of  this  locality  shows  6  feet  of  gyp- 
sum, containing  disseminated  sulphur,  underlain  by  3  feet  of  bitumi- 
nous limestone, 
South  of  Delaware  Creek,  about  1  miles  southeast  of  Delaware 
Spring  and  18  miles  northwest  of  Rustler  Spring,  is  a  prominent 
three-peaked  hill  of  limestone  underlain  by  gypsum.  A  cavern  over 
100  feet  deep  shows  surficial  alteration  of  the  limestone  into  white, 
porous  gypsum,  with  which  thin  coatings  of  native  sulphur  are  asso- 
ciated. The  odor  of  hydrogen  sulphide  is  easily  detected  in  the 
cavern,  and  apparently  the  alteration  of  the  limestone  and  the  origin 
of  the  sulphur  are  due  to  that  gas. 
Sulphur  also  occurs  in  small  quantities,  disseminated  in  gypsum, 
about  10  miles  north  of  Rustler  Springs,  near  Stinking  Seep;  and 
on  the  north  side  of  Cottonwood  Draw,  about  16  miles  northwest  of 
Toyah,  contiguous  to  the  oil  wells  in  Toyah  basin,  a  small  area  has 
been  scraped,  exposing  some  sulphur  sparingly  disseminated  in  sec- 
ondary gypsum.  A  few  other  localities  are  also  known  where  sul- 
phur is  present  at  the  surface. associated  with  gypsum,  but  little  pros- 
pecting has  been  done  at  these  places. 
These  are  practically  all  of  the  known  occurrences  of  sulphur  in 
this  region.  Sulphur  is  found  throughout  a  wide  area,  and  locally  it 
is  fairly  well  concentrated,  but  very  little  is  known  of  the  extent  and 
value  of  these  deposits.  Judging  from  the  occurrences  noted  above, 
there  is  not  a  great  quantity  of  sulphur  in  sight,  Apparently,  how- 
ever, economical  mining  on  a  small  scale  would  yield  some  profit,  and 
in  this  way  the  deposits  might  well  be  further  explored.  The  value 
of  this  field  can  be  determined  only  by  persistent  prospecting. 
Concerning  the  origin  of  the  sulphur,  the  most  significant  facts 
seem  to  be  its  association  with  gypsum  and  organic  matter  and  the 
occurrence  of  hydrogen  sulphide.  There  has  been  no  recent  volcanic 
ictivity  in  this  region. 
The  association  of  sulphur,  gypsum,  and  organic  matte1!*  suggests 
heir  genetic  relationship,  inasmuch  as  sulphur  can  be  formed  by  the 
Bull,  260—05  m 3§ 
