eckel.]    CEMENT-ROCK   DEPOSITS  OF  LEHIGH  DISTRICT,   PA.-N.   J.    451 
The  specimens  whose  analyses  are  given  above  were  mostly  from 
the  vicinity  of  Belvidere,  N.  J.,  and,  though  representative  in  other 
respects,  seem  to  have  been  rather  lower  in  magnesia  than  the  usual 
run  of  the  Trenton  limestone  in  the  Lehigh  district. 
Magnesian  Kittatinny  limestone. — Underlying"  the  cement-rock 
series  is  a  very  thick  formation  consisting  of  light-gray  to  light-blue 
massive-bedded  limestone,  with  frequent  beds  of  chert.  These  lime- 
stones are  predominantly  highly  magnesian,  though  occasionally  beds 
of  pure  nonmagnesian  limestone  will  be  found  in  the  series.  The 
magnesian  beds  are,  of  course,  valueless  for  Portland-cement  man- 
ufacture, but  the  pure  limestone  beds  furnish  part  of  the  limestone 
used  in  the  Lehigh  district  for  addition  to  the  cement  rock.  An  ex- 
cellent example  of  this  is  furnished  by  the  quarry  near  the  east  bank 
of  Lehigh  River,  just  above  Catasauqua.  In  this  quarry  most  of  the 
beds  are  highly  magnesian,  and  are  therefore  useful  only  for  road 
metal  and  flux;  but  a  few  pure  limestone  beds  occur,  and  the  material 
from  these  low-magnesia  beds  is  shipped  to  a  neighboring  cement  mill. 
Numerous  analyses  of  the  highly  magnesian  limestones  are  avail- 
able, from  which  a  few  typical  results  have  been  selected  for  insertion 
here.  Analyses  of  the  purer  limestone,  used  to  add  to  the  cement 
rock,  will  be  found  in  the  table  on  page  452. 
Analyses  of  magnesian  Kittatinny  limestone.0' 
Silica  (Si02)  
Alumina  (A1203) 
Iron  oxide  (Fe203)..- 
Lime  (CaO) 
Magnesia  (MgO) 
Carbon  dioxide  (C02) 
Per  ct. 
9.9 
1.7 
27.6 
17.9 
41.9 
Per  ct. 
1.7 
28.5 
17.3 
41.5 
Per  ct. 
8.8 
29.4 
17.8 
42.8 
Per  ct. 
5.5 
1.3 
28.2 
20.2 
44.3 
Per  ct. 
9.8 
3.7 
26.4 
15.1 
45.0 
Per  ct. 
4.9 
6.5 
27.3 
14.6 
44.8 
Per  ct. 
2.0 
8.4 
32.4 
15.5 
42.5 
Per  ct. 
8.0 
5.3 
26.3 
17.4 
41.1 
Per  ct. 
4.1 
1.6 
30.3 
18.3 
44.1 
Per  ct. 
16.9 
1.0 
28.3 
15.3 
38.9 
1.  Chandlers  Island,  Sussex  County,  N.  J. 
2.  Sparta,  Sussex  County,  N.  J. 
3.  Asbury,  Warren  County,  N.  J. 
4.  Oxford  Furnace,  Sussex  County,  N.  J. 
5,6.  Clinton,  Hunterdon  County,  N.  J. 
7.  Pottersville,  Somerset  County,  N.  J. 
8, 9.  Peapack,  N.  J. 
10.  Annandale,  N.  J. 
While  all  of  the  above  analyses  are  from  New  Jersey  localities  the 
magnesian  limestone  of  the  rest  of  the  Lehigh  district  would  give 
closely  similar  results. 
THE    CEMENT    INDUSTRY    IN    THE    LEHIGH    DISTRICT. 
Combination  of  materials  used. — Throughout  most  of  the  Lehigh 
district  the  practice  is  to  mix  with  a  relatively  large  amount  of  the 
"cement  rock"  or  argillaceous  limestone  a  small  amount  of  pure 
limestone,  in  order  to  bring  the  lime  carbonate  content  up  to 
the   percentage  proper  for   a   Portland-cement   mixture.     As  above 
a  From  various  reports  of  the  New  Jersey  Geological  Survey. 
