'A'A NKW VOlMv STATE MISKTM 



ollicc is the oiilv one in \\iii(li this rock lias Ikhh (luarried to any 

 cxlt'iM. Uciiiii' of a radicr coarse jriain. it serves well for founda- 

 tions and will dress readily. Some of the beds are of sufficient 

 thiekness to form jjjood blocks. The strata immediately above this 

 bed are quarried a short distance south by Mr Yronian, the rock 

 having been used for foundation in the new Schoharie schoolhouse. 

 Somewhat hiji^her uj) in the field the higher Kondout beds are 

 taken out. The only locality where the Rondout waterlime is 

 extensively quarried in this region is at How'es Cave, where the 

 Helderberg Cement Company uses this rock for the manufacture 

 0if natural or Rosendale cement. The stratum used lies just above 

 the Cobleskill and is six feet thick. An analysis of this lime- 

 stone gave '^ 



Lime carbonate 55 . 17 



Magnesium carbonate 19 . 71 



Silica 12.89 



Ferric oxid and alumina 11.15 



Water GG 



Loss .42 



Total 100. 



At this locality the beds immediately succeeding the cement 

 bed and for nearly 50 feet above it are not utilized. Above this 

 about 3G feet of Manlius and about 30 feet of Coeymans occur. 

 These are quarried together and manufactured into Portland 

 cement. While the natural cement rock has been used for a long 

 period of time for the manufacture of natural cement, the Port- 

 land cement industry only began here in 1898. It was com- 

 menced on a small scale, but rapidly grew as the demand for 

 Portland cement increased. In 1900 a new plant with a nominal 

 capacity of 1500 barrels a day was exacted. The process of manu- 

 facturing the cement is as follows : 



The limestones is crushed and mixed with the proper amount of 

 clay in the j)resence of water by what is known as the " w^et 

 process ". This is done in cylindric tanks in the center of each 



'Kios. N. Y. state Mns. Bnl. 44, p. 817. 



