250 W. S. BAYLEY — SYENITES FROM NEW ENGLAND. 



Aii analysis of the rock made by the same chemist gave: 



Si0 2 59.01 



Ti0 2 81 



Al,,(> 3 L8.18 



Fe 2 3 L.63 



FeO 3.65 



MnO 03 



CaO 2.40 



SrO tr. 



BaO OS 



MgO 1.05 



K.,0 5.34 



Na 2 7.03 



ZrO tr. 



B 2 O(atl00°) 15 



li.,0 (above 100°) 50 



P-A tr. 



CI 12 



Total 99.98 



A single glance at this column affirms the statement above made that 

 if any plagioclase other than albite is present in the rock it must be in 

 very small quantity, for the 2.40 per cent of CaO indicated by the analysis 

 is not more than enough to satisfy the demands of the 15 per cent of 

 augite, hornblende, biotite and sphene that are known to exist there. 

 Again, the percentage of K,0 is less than that of Na 2 0. Even after allow- 

 ing for the excess of Xa,0 over K.,0 in the eleolite and the presence of 

 sodium in the sodalite, there still would remain a larger proportion of 

 Xa.,0 than of K.,0. This would necessarily imply that albite is in excess 

 over orthoclase. 



Summary. — Although but few specimens of the Red hill, New Hamp- 

 shire, rock have been examined, enough is known of the occurrence to 

 enable us to declare it to be an acid eleolite-syenite, containing a larger 

 proportion of albite than of orthoclase. Its essential constituents in the 

 order of their ages are augite, hornblende, biotite, sodalite, eleolite and 

 the two feldspars, orthoclase and albite. Its accessory primary compo- 

 nents arc apatite, crystallized sphene, magnetite and occasionally zircon, 

 and its secondary constituents granular sphene and bright-green horn- 

 blende, besides fibrous decomposition products of eleolite and of ortho- 

 clase. It differs from litchfieldite in being less acid, in containing a little 

 less albite and more undoubtedly original orthoclase, and especially in the 

 possession of augite, hornblende and sphene, all of which are important 

 elements in the composition of most eleolite-syenites. Besides, the New 



