CRUSHING TESTS OF THE BECKET GRANITOID GNEISS. 

 Analysis of granite from quarries at Becket, Massachusetts. 



37 



Moisture at 110° C 



Loss on ignition 



SiO; 



Fe.O;, 



Al.O:, 



MuO 



CaO 



K.O. 



S.... 



Per cent. 



0.08 



.74 



69, 46') 



2.30 

 17.50 

 Trace. 



2.57 



.305 



4.07 

 .04 



Na^O by difference 



97.07 

 2.93 



" Crushing tests were made on five sample cubes with the Emory testing 

 machine in the School of Mines, and as preparatory to this the specific 

 gravity was found on four cubes at 2.688, 2.687, 2.684, and 2.688. After 

 three weeks' soaking these cubes absorl)ed water, respectively, 0.0021, 

 0.0021, 0.00224, and 0.0026 per cent. The cubes were first gimmd and 

 polished so that the faces next the jaws of the crusher were parallel within 

 a limit of error of 0.005 inch. The cushion employed between the cubes 

 and the jaws was blotting paper. The crushing tests gave the following 

 results : 



Crushing tests of granite from quarries at Becket, Massachusetts. 



Height inches.. 



Breadth inches . . 



Thickness inches . . 



Area sq. inches.. 



Maximum compression jioiinds . . 



Crushing strength per sq. inch.. 



2.011 

 1.97 

 2.03 

 4.0 

 101, 400 

 25, 350 



2.009 

 2.03 

 2.03 

 4.12 

 108, 700 

 26,383 



' ' The cubes exploded without previous cracking. This strength is excep- 

 tionally high, as the general run of granite is far less. It does not, however, 

 equal the elaiolite-syenite of Little Rock, Arkansas, which was tested by the 

 late J. Francis Williams (see Annual Report of Arkansas State Geologist, 



