234 
CONTRIBUTIONS   TO   ECONOMIC   GEOLOGY,  1904.        [bull.  26( 
Classification  and  synonymy  of  the  formations  of  the  "Magnesian  "  or  "Ozark" 
series  in  Missouri. 
Period, 
Series. 
Ill 
Formation. 
Joachim  limestone 
St.  Peter  ("Crystal  City") 
sandstone. 
Jefferson  City  limestone . 
Roubidoux  formation. 
Gasconade  limestone . 
Elvins  formation. 
Bonne  Terre  limestone 
La  Motte  sandstone 
Thick- 
0-150 
0-200 
50-250 
70  225 
150  650 
Synonyms. 
[First  Magnesian  limestone. 
[Folley  limestone.** 
First  or  Saccharoidal  sandstone. 
Cap  an  Gres  sandstone. 
Pacific  sandstone. 
"Key    sandstone1'  in  Yellville 
district  of  Arkansas. 
Second  Magnesian  limestone. 
Winfield  limestone. 
Finley  limestone.  & 
?  Marsh.fi.eld  sandstone. 
Second  sandstone. 
Morean  sandstone. 
St.  Elizabeth  formation  and 
Bolin  Creek  sandstone  mem- 
ber. 
?  Marshfield  sandstone. 
?  Bolivar  sandstone. 
Third  and  Fourth  Magnesian 
limestones  and  Third  sandst. 
Includes  Osage  limestone,  Cole 
Camp  sandstone  of  Winslow; 
also  Gasconade  limestone, 
Gunter  sandstone,  and  Proctor 
limestone,  of  Ball  and  Smith. 
Lesueur  limestone. 
0  120 
0-400+ 
0-300 
Ba^al  part  of  the  Potosi  lime- 
stone and  the  "Potosi  slates 
and  conglomerates  "  of  Nason. 
?  Fourth    Magnesian   limestone 
in  -part. 
Fredericktown  limestone. 
Bonne  Terre  limestone. 
.Decaturville  limestone. 
Second  sandstone  of  Shumard 
in  part. 
Archean  granites  and  porphyries. 
a  The  names  Folley  limestone,  Cap  au  Gres  sandstone,  and  Winfield  limestone,  together  witM 
a  number  of  other  new  names,  were  published  by  Keyes  in  1898,  in  a  paper  entitled  Some  Geo! 
logical  Formations  of  the  Cap  au  Gres  Uplift:  Proc.  Iowa  Acad.  Sci.,  vol.  5,  pp.  58-63. 
b  The  names  Finley  limestone,  Marshfield  sandstone,  and  Decaturville  limestone  appear  in  a 
provisional  table  of  geological  formations  in  Missouri  published  by  Shepard  in  1904:  Bull.  Brad. 
Geol.  Field  Sta.,  p.  42. 
The  deposits. — The  Ste.  Genevieve  copper  mines  are  not  now  in 
operation.  They  have  been  described  by  Mr.  F.  L.  Nicholson."  The! 
principal  deposit  occurs  as  a  bedded  chert  breccia  in  the  lower  pari 
of  the  Jefferson  City  limestone.  Copper,  in  the  form  mainly  of  ehal-j 
copyrite  and  malachite,  forms  the  cement  of  the  breccia.  The  bed 
where  seen  varies  in  thickness  from  18  inches  to  3  feet.  The  recent 
completion  of  the  Southern  Missouri  Railway  to  within  3  miles  of 
the  deposits  so  alters  the  mining  conditions  that  the  deposit  is  believed 
to  be  worthy  of  further  prospecting,  and  to  that  end  drilling  is 
recommended. 
At  Mine  la  Motte  the  copper  occurs  as  chalcopyrite  in  low  percent-i 
age,  intimately  intermingled  with  galena.     Its  production  is  largely 
"  Nicholson,  Frank  L.,  A  review  of  the  Ste.  Genevieve  copper  deposits  :  Trans.  Am. 
Inst.  Min.  Eng.,  vol.  10,  1882,  pp.  444-45G. 
