34 NEW YORK STATE MUSEUM 



material that can be readily quarried ; the physical conditions affect- 

 ing the course and economy of quarry work ; and the general char- 

 acter of the stone with regard to color, texture and the larger 

 structural variations incident to inclusions, segregations, dikes and 

 veins. Even liberal samples collected with a great deal of care fail 

 to convey the same information respecting the general features 

 of the stone that is gained by an inspection of the exposure or 

 quarry pit itself. 



The next consideration is to establish the physical properties 

 of the stone so as to be able to forecast with some certainty its 

 relative fitness for the special service that may be demanded of it. 

 This information is afforded by mineralogical and chemical investi- 

 gations supplemented by physical tests along the line of those 

 adopted for estimating the strength and durability of other struc- 

 tural materials. Furthermore, a comparative study of the behavior 

 of different quarry stones under conditions of actual service will 

 be helpful in applying the results obtained by laboratory experi- 

 mentation. In fact, physical tests alone may lead to erroneous 

 conclusions as to the relative value of samples, and the guidance 

 .obtainable by observations of materials of similar nature in actual 

 service is highly essential in forming an estimasbe. 



QUARRY OBSERVATIONS 



The field relations of quarry stones may be said to comprehend 

 practically the whole range of variations of rock occurrence. Their 

 interpretation requires a broad knowledge of the origin and struc- 

 ture of rocks and the modifications produced by surface agencies 

 which can hardly be presented here. Such knowledge is in part to 

 be found in any standard work on geology and in part rests upon 

 personal experience gained by study in the field. Only a few gen- 

 eral matters will be given attention here. 



The granites and related igneous rocks ordinarily occur in large 

 bodies and are continuous for indefinite distances into the earth. 

 The question of quantity of material is not so important, therefore, 

 as the situation with respect to ease of quarrying. The most ad- 

 vantageous situation for cjuarry work is along the side of a hill, 

 as it facilitates the handling of the stone and secures natural drain- 

 age. The direction and frequency of joints exert much influence 

 upon the relative ease of obtaining blocks and also determine 

 whether stone of size for building and monumental work can be 

 had. A rift and grain structure is necessary if the stone is to be 

 used for dimension work or paving blocks. 



