24  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,   PART    T. 
data  on  the  limestones  of  that  region.  In  two  brief  papers  published 
in  the  present  bulletin  the  principal  facts  relative  to  the  use  of  these 
limestones  as  fluxing  materials  and  for  lime  burning  are  summarized. 
Magnesia  and  magnesite. — During  the  last  fall  Frank  L.  I  less  con- 
tinued his  investigations  of  the  magnesite  deposits  of  California. 
The  results  of  this  work  are  not  in  shape  for  publication  at  present, 
but  a  special  bulletin  on  the  subject  will  probably  be  issued  by  the 
Survey  in  1907  or  .1908. 
(i]ipsum  and  plasters. — Various  gypsum  districts  have  been  visited 
by  Survey  geologists  during  the  past  year,  and  a  report  on  one  west- 
ern district  is  contained  in  the  present  bulletin.  During  the  coming 
year  an  attempt  will  be  made  to  prepare  a  revised  edition  of  Bulletin 
223,  on  the  gypsum  deposits  <>f  the  United  States. 
Chins.  A  number  of  reports  on  the  clay  resources  of  various  parts 
of  the  United  States  are  included  in  the  present  bulletin.  Most  of 
the  investigations  covered  by  these  reports  were  carried  on  by  geolo- 
gists engaged  in  area]  work  for  geologic  folios,  but  the  work  and  the 
papers  by  Messrs.  John  'P.  Porter  and  Otto  Yeatch  form  exceptions  to 
this  rule. 
Building  stone.  T.  Nelson  Dale  has  continued  his  studies  of  the 
granite  deposits  of  New  England,  and  is  preparing  a  detailed  report 
on  the  subject  for  publication  during  the  coming  year  as  a  bulletin 
of  the  Survey.  The  present  bulletin  includes  a  brief  summary  of 
this  report . 
MISCELLANEOUS   NONMETALS. 
Glass  sand.  The  glass-making  materials  of  several  areas  were 
studied  by  Survey  geologists  during  L905,  and  the  economic  bulletin 
(No.  285)  for  that  year  contained  three  detailed  reports  summarizing 
the  results  of  their  investigation.  Mr.  Burchard  continued  this  work 
in  1906  and  presents  two  reports  in  the  present  bulletin.  In  the 
course  of  this  work  he  has  carried  out  chemical  and  physical  tests, 
not  only  of  glass  sands  now  in  use,  but  of  sands  from  undeveloped 
deposits  which  seem  to  be  available  for  use  as  glass-making  material. 
It  is  believed  that  this  investigation,  which  is  of  a  type  somewhat 
different  from  those  usually  undertaken  by  the  Survey,  will  yield 
results  so  valuable  that  its  continuance  is  warranted. 
Feldspar  and  quartz. — Reports  on  the  feldspar  and  quartz  deposits 
of  two  areas,  by  E.  S.  Bastin,  are  included  in  this  bulletin.  These 
represent,  so  far  as  known,  the  first  serious  studies  of  this  interesting 
group  of  mineral  products  and  will  probably  prove  serviceable  to 
those  who  are  engaged  in  prospecting  or  working  similar  deposits 
in  other  districts. 
Mica. — Papers  on  mica  deposits  in  Wyoming  and  North  Carolina, 
by  Messrs.  Ball  and  Sterrett,  respectively,  will  be  found  in  this  bid- 
