22 



Day, etc. — Determination of Mineral 



the true increase. At 20° the true specific volume of cristo- 

 balite is 13*4 per cent greater than that of quartz. 



7. Granite. 



Three specimens of granite were used : (1) a hornblende 

 granite from Copper Mt., Alaska (JS r o. 128) ; (2) a pink coarse- 

 grained quartzose granite from Kasaan Peninsula, Alaska 

 (C. W. Wright No. 39); (3) a gray biotite-muscovite. granite 

 from Stone Mountain, Georgia. The latter was furnished us 



Fig. 7. 



• iz 400 



CD 





















x — 



— 



EXPERIMENTAL DATA 







i / 





SPE 



CIRC VOLUME 

 GRANITE 



OF 





^ 



$ / 



• 































#^ / 

























__s- 





^ 



^H*. 



5E CONOj^^-^ 













GRANITE^— -- 

















| 



















TEMPER 



ATURE 

















lOO 200 300 400 500 600 700 800 900 lOOO 



in the form of two large blocks by the Stone Mt. Granite Co. 

 of Atlanta. 



The first specimen was used only for a preliminary measure- 

 ment. The second was tested under tin to 618° in the metal- 

 frame apparatus (page 15). The third was tested to 935° in 

 the graphite apparatus. The results are plotted in fig. 7. 



In both of the granites that were heated above 575°, the 

 rapid volume increase on approaching that temperature is 

 notable. This increase is to be expected from the presence of 

 free quartz in the granite, but its amount is unexpectedly 



