210  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,    1903,  [bull.22E 
At  Jefferson  City,  formerly  Mossy  Creek,  is  located  the  most  extern 
sive  mine  of  the  region,  which  was  opened  about  1860.  The  carbonate 
and  silicate  were  manufactured  into  zinc  oxide.  This  was  soon  closed 
down,  but  operations  have  been  resumed  at  several  different  times  in 
taking  out  the  blende  below  the  surface  ores.  No  work  has  been  done 
for  several  years.  In  this  mine  the  ore  has  been  taken  out  from  a 
series  of  large  open  cuts.  These  cover  an  area  about  600  by  75  feet 
and  are  from  20  to  40  feet  deep.  The  rock  was  blasted  out  and  sorted 
bv  hand.  The  best  material  was  crushed  and  the  blende  was  concen- 
trated by  washing.  Water  for  the  purpose  was  abundant  in  Mossy 
Creek,  which  flowed  past  the  mine.  The  ore  was  not  reduced  at  the 
mine,  but  was  all  shipped  away  for  smelting. 
In  L898  interest  was  revived  in  the  zinc  deposits,  and  mining  opera- 
tions were  begun  14  miles  southeast  of  Newmarket,  5  miles  northeast 
of  Knoxville,  and  at  McMillan.  The  operations  at  Newmarket  were 
discontinued  after  the  rock  and  ore  had  been  removed  from  an  open 
cut  about  80  feet  in  diameter  and  30  feet  deep.  A  mill  wTas  erected 
and  the  ore  crushed  and  washed  at  the  mine.  A  great  drawback  to 
successful  work  was  the  scarcity  of  water.  The  mine  was  situated  on 
a  hillside  in  low,  rolling  country,  and  the  only  neighboring  stream  was 
below  the  mine  and  practically  dried  up  during  droughts.  Operations 
5  miles  northeast  of  Knoxville  consisted  of  the  sinking  of  a  shaft  and 
several  test  pits.  No  great  amount  of  ore  was  handled,  and  work  was 
soon  discontinued.  Loves  Creek  flows  past  the  mine  and  furnishes 
sufficient  water.  At  McMillan  an  open  cut  was  made  in  a  good  body 
of  ore. 
In  L900  work  was  begun  on  the  blende  by  the  Rosebeny  Zinc 
Company  on  the  site  of  old  workings  1^  miles  west  of  Mascot.  In 
1908  the  Holston  Zinc  Company  began  operations  in  both  blende  and 
carbonate  ore  one-half  mile  west  of  Mascot.  Both  of  these  mines  are 
being  worked  at  present  through  open  cuts,  though  short  tunnels  have 
been  driven  at  the  Roseberry  mine  to  verify  the  extent  of  the  ore. 
At  the  Roseberry  mine  the  open  cuts  are  200  by  50  feet;  at  the  Hol- 
ston mine  they  are  100  by  25  feet.  A  mill  has  been  erected  at  each 
mine  to  crush  the  rock  and  wash  out  the  blende,  but  none  of  the  ore 
is  reduced  at  the  mines.  Each  mine  is  situated  on  a  creek  which  sup- 
plies water  for  concentrating. 
Nature  of  the  deposits. — The  ores  of  zinc  consist  of  the  sulphide, 
blende,  of  the  carbonate,  smithsonite,  and  of  the  hydrous  silicate, 
calamine.  The  carbonate  and  silicate  are  not  found  deeper  than  20 
feet,  and  were  formed  from  the  blende  by  various  weathering  pro- 
cesses, primarily  oxidation.  Much  calcite  was  dissolved  in  this  opera- 
tion, leaving  open  spaces  and  veins  lined  with  crusts  of  the  silicate 
and  carbonate.  The  process  of  transformation  from  the  blende  to 
these  minerals  is  readily  apparent  in  all  its  stages.     In  their  formation 
