i?*sson and Washington — Geology of New Hampshire. 439 



Art XXXVIII. — Contributions to the Geology of New Hamp- 

 shire: No. 11^ Petrography of the Belknap Mountains ; by 

 L. V. Pirsso^ and H. S. Washington". 



Ix a former paper* we presented the results of our studies 

 in the held of the igneous rock masses composing the Belknap 

 Mts. in Xew Hampshire, and in the present one we purpose to 

 give the results of our investigations of them in the labora- 

 tory by microscopic and chemical methods. We have found 

 that the following rocks, classified both in the quantitative 

 and in the older systems, are present : 



Class Order Eang 



Persalane Britannare Liparase 



Persalane Britannare Toscanase 



Persalane Canadare Pulaskase - 



Dosalane Germanare Monzonase 



Salfemane Gallare Camptonase 



Snbrang . Older System 



Liparose (I. 4.1.3) Aplite 



Lassenose (I. 4.2.4) Adamellite 



Pulaskose (I. 5.2.3) Syenite 



Akerose (II. 5.2.4) Spessartite 



Camptonose (III. 5.3.4) Essexite and Camptonite 



These will be described in the above order and the article 

 will end with a discussion of the petrologic history and of the 

 chemical characters of the district. 



Liparase. Aplites. 



As previously stated in the foregoing geological description 

 of the district, the Belknap massif and the surrounding rneta- 

 morphic rocks are cut by dikes and intrusions of fine-grained 

 to dense granitic, quartzose rocks, whose general characters 

 place them under this rang. In Rosenbusch's system of classi- 

 fication they would be aplites, both in the broader and in the 

 more special application of this term. A similar material 

 serves also as the cement of the brecciated zone on Locke's 

 Hill. They have all been studied in thin section, but for pur- 

 poses of chemical analysis an average type has been selected 

 whose description follows herewith. 



JBiotitic-grano-liparose {ciplite). 



Locality. — Dike on upper southwest slope of Mt. Belknap. 

 Megascopic. — Phanerocrystalline ; fine-grained ; flesh-col- 

 ored ; persalic and dominantly feldspathic ; faintly dotted with 

 *This Journal, vol. xx, pp. 344-352, 1905.- 



