NOTES ON THE GYPSUM INDUSTRY OF NEW YORK 



Introduction 



In presenting this sketch of the gypsum industry of New York 

 State, the wi^iter desires to say that the greater part of the his- 

 tory, geology and technology is a compilation of information 

 already published. 



The description of the New York State mines and mills is based 

 on field work performed by him. At this time, he wishes to thank 

 the producers of gypsum for the facilities for study which were 

 placed at his disposal and the uniform courtesy which has been 

 extended to him. In particular he desires to thank Mr F. M. 

 Severance, who has furnished much historical data in regard to 

 the Fayetteville deposits. 



The publications which have been most largely drawn on are 

 Grimsley's Special Report on Kansas Gypsum^ Knapp's Chemical 

 Technology, Wagner^s Chemical Technology and New York State 

 Museum bulletin 11. 



Gypsum. Gypsum, the hydrous sulfate of lime, has the chem- 

 ical formula OaSO^ + 2H2O and, when pure, contains 32.5^ of lime 

 (CaO) 46.6^ of sulfur trioxid (SO3) and 20.9^ of water (H2O). It 

 occurs both in isolated crystals and in large masses of apparently 

 amorphous Tock, though even the most compact varieties show 

 cleavage planes and crystal faces under the microscope. It is 

 one of the softest minerals, and is easih^ scratched with the thumb 

 nail or cut with a knife. In the Mohs scale of hardness it is given 

 as 2, graphite being 1 and diamond 10. 



Gypsum crystallizes in the monoclinic system, the crystals being 

 usually tabular or prismatic with pyramidal terminations. Twin 

 crystals are very common. It has a perfect cleavage and from 

 the moonlike luster of the cleavage surfaces is derived the name 

 selenite (Greek (reXrj^rj) which is applied to the clear crystals 

 and platelike cleavages. 



