Building Stone 



This important class of material has been discussed at length 

 by Prof. John C. Smock in Bulletins Nos. 3 and 10 of the New 

 York State Museum, and these two publications contain nearly 

 all that is known at present. 



Since Bulletin No. 10 is out of print a large portion of it has 

 been incorporated in the following pages. 



The directory of producers gives the latest information. 



GEOLOGY AND* GEOGRAPHIC DISTRIBUTION OF 

 BUILDING STONE IN NEW YORK, 



By John C. Smock. Revised by F. J. H. Merrill. 



GRANITIC ROCKS 



Granites, Gneisses, Syenites, Trap-Rock and Norites. 

 Granites. Typical granite is a crystalline, granular mix- 

 ture of feldspar, quartz and hornblende. In addition to these 

 essential constituents, one or more accessory minerals may 

 be present. The more common are the micas, muscovite and 

 biotite, garnet, tourmaline, magnetite and pyrite. The character 

 of the rock is often determined by the presence of these acces- 

 sory constituents in quantity, as in some cases the hornblende is 

 entirely replaced by mica. 



The chemical composition also varies from that of the average 

 or typical kind. The mineral ogical differences mark the varieties, 

 thus there are : hornblende granite, biotite granite, tourmaline 

 granite, etc. 



The texture of granites is determined by the aggregated 

 miaerals entering into their composition. They vary from 

 coarse-crystalline, in which the individual crystals may be an 

 inch or more in length, to fine-crystalline and aphanitic, wherein 

 the minerals are hardly visible to the eye. In consequence of 

 the wide variation due to the mode of arrangement of the 



