QUARRY MATERIALS OF NEW YORK 147 



Chemical analysis. The following is an analysis of the Little 

 Falls syenite extracted from N. Y. State Museum Bulletin 115, the 

 analyst being E. W. Morley : 



SiOa 66.72 



AUDs I6.I5 



Fe 2 Oa 1.23 



FeO 2.19 



MgO 73 



CaO 2.30 



NaoO 4-36 



K 2 5-66 



H 2 77 



MnO .07 



100.18 

 The analysis is undoubtedly based on samples of the more quartz- 

 ose rock. 



Physical tests. Numerous tests of the Little Falls syenite have 

 been made by the bureau of research, State Department of High- 

 ways. The following table gives the maximum and minimum and 

 average results of eleven different tests : 



Maximum Minimum Average 



Specific gravity 2 . 93 2 . 75 2 . 80 



Weight pounds for each cubic foot 183 172 175 



Absorption, pounds for each cubic foot .21 .09 .15 



Per cent of wear 4 2.6 3.3 



Hardness 18.4 17.8 18. 1 



Toughness 14 8'. 5 11. 7 



Diabase dike. The dike that has been mentioned as intersecting 

 the syenite is found in a slight depression of the surface about 

 1000 feet west of the Syenite Trap Rock quarry. It shows also in 

 the face of the cliffs above the Dolgeville railroad cut and can be 

 traced thence northeasterly toward the Little Falls road, but is 

 concealed near the road itself if it reaches that far. The dike has 

 been intruded along the course of the main jointing which here 

 is N. 30 E. ; the map in Cushing's bulletin, however, indicates the 

 strike as nearly east and west. Within the exposed section, it 

 measures about 125 feet in width, which may be taken as about 

 the actual thickness. It thus could be quarried without difficulty. 

 It ranges from very fine, even, glassy texture near the contact to 

 a rather coarse grain with porphyritic feldspars an inch or so long 

 in the interior of the body. Though somewhat altered in the out- 

 crop, pieces give a metallic ring when struck, like a hard trap. Its 

 mineral composition may be described as consisting of plagioclase, 

 augite and magnetite, with secondary serpentine and chlorite. 

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