Pirsson an d Washington — Geology of New Hampshire. 501 



cent of the mineral to be present ; this is due to the fact that 

 the needles of the mineral are excessively minute and cannot 

 be measured accurately. In the same way, many tiny necks 

 of calcite also escaped, and this is probably also low. With 

 the feldspar is included a small amount of isotropic base pre- 

 viously mentioned. All of these errors are small, however, 

 and the result shows the rock made up of iron ore, horn- 

 blende and plagioclase in about the proportions given. 



Chemical Composition. — This is shown in analysis No. I of 

 the above table. In Nos. II-V are given for comparison 

 analyses of rocks of similar mineral composition and occur- 

 rence which are either in camptonose or immediately adjoin- 

 ing subrangs. They are all classed as camptonites in the older 

 systems. These are from the New England province and 

 there is a strong resemblance between them in essential fea- 

 tures. In No. Ill the total alkalies are about the same as in 

 the others, but the soda very strongly predominates, throwing 

 the rock over into the persodic subrang in the lendofelic order 

 (III, 6.3.5), which is as yet unnamed! but for which we pro- 

 pose the name of livermorose, from the locality of Livermore 

 Falls. Under the head of rocks which have been classed as 

 camptonites in the qualitative systems, it will be found by a 

 study of the analyses that types have been classed together 

 which show quite wide divergences in chemical composition. 

 When one recalls, however, that the type in such systems is 

 based mineralogically upon the association of plagioclase with 

 a relatively large amount of brown hornblende, this is not to 

 be wondered at, for these brown hornblendes present as large 

 a range of chemical variation as can usually be found under 

 the heading of a single mineral name. 



Classification. — In the quantitative system the norm of the 

 rock and its position are as follows : 



Norm 



Or .. 13-34 Sal 55*80 , x „ „ 



Ab ..20-44 F^m~ = 3TbT = 1 " 5 (3) ' Salfemane 

 Ne .. 3-12 L 3-12 , x _ .. 



Ad .. 18-90 IT" = 52^8 = °'° 5 = (5) ' 



Di .. 13-90 K' 2 0' + Na Q 0' 73 



01 . .. 7-11 CaO' = 63 = Vl = (3) ' Cam P tona8e 



Mt ... 5-80 KO' 24 , , _ 



11 .... 8-21 Na(y = ^b= °' 48 = ( 4 >' Camptonose 



Ap .. 2.02 

 Rest.. T'5Y 



Total, 100-41 



