24 HENRY S. WASHINGTON 



Classification. — The norm of this rock, calculated from the figures 

 shown in the analysis, is as follows: 



Norm Ratios 



Or 9 



Ab. 23 



An 18 



Ne 4 



Di 17 



01 13 



Mt 4 



II 7 



Ap I 



Rest o 



99 



^^ ^T^= of = i-27. Class III, salfemane. 



32 Fern 43.80 



35 F 51.12 ^ ^ , ,, 



40 L ""Tlo == ^ ^ • ^^- ^^^^^ 5, gallare. 



°5 K^O + Na^O 77 



53 CaO^ ^66 ^ ^ • ^ ^- ^"^ ^' camptonase. 



64 



3° Vt~^=^=o-28. Subrang 4, camptonose. 

 JNazO 00 



Symbol, III. 5. 3. 4- 



77 



This rock, therefore, falls well within the salfemane class, the 

 amount of nephehte being negUgible, and it is also clearly in the per- 

 felic order, the alkaHcalcic rang, and the dosodic subrang, and is thus 

 an almost central camptonose. 



The relations of the norm and mode, which are almost identical 

 with those discussed above, need not be repeated here. The mode 

 may be considered as normative, and the type may be briefly described 

 as an alferfemphyro-camptonose. 



CAMPTONOSE (OLIVINE-BASALT), MONTE RANERI TYPE 



Megascopic characters. — This type differs from the preceding in 

 the abundance and size of the oh vine phenocrysts, which are olive- 

 green in color, from 2 to 10"^"^ in diameter, and constitute at least 20 

 per cent, of the rock. Feldspar phenocrysts are tabular, as -in the 

 salphyric subtype just described, but their number is very few, and 

 they are small and inconspicuous, as are also the phenocrysts of augite. 

 Most of the specimens of this type which were collected are compact, 

 but scoriaceous and vesicular forms also occur. On weathering, 

 the compact forms show a feature which was also noted in some of 

 the Catalan basalts, namely a peculiar mottled appearance in patches 

 of dark and light gray, or dark gray and sHghtly reddish gray, the 

 rock tending also to disintegrate into small, angular pieces which 

 correspond to these colored areas. This appearance, which has 

 been called Sonnenbrand by German quarrymen, is not uncommon 



