230 Washington — Catalan Volca/noes and the it' Rocks. 



locality and the suffix -al, but they will be considered as merely 

 provisional and applicable only to the rocks described in this 

 paper, and indicated by the use of a locality name alone, with- 

 out any suffix. This method is adopted for the reason that, in 

 the case of such basaltic rocks, whose modal and textural fea- 

 tures present no marked peculiarities, but can be duplicated 

 in many rocks from well-known localities, and some of which 

 hare been thoroughly studied in the earlier days of the science, 

 it does not seem fitting that the systematic, typal adjectives 

 should be based upon these little known and as yet imperfectly 

 described occurrences. 



If the quantitative system of classification, or some modifi- 

 cation of it, is eventually adopted by petrographers generally, 

 it will be the task of some future master of the science to 

 undertake the comparative study of igneous rocks and the 

 coordination of the various types, the distinctive typal adjec- 

 tives being bestowed with judicious consideration of all the 

 facts as to which locality is the most representative, the best 

 studied, or the longest known. For the present, in the applica- 

 tion of the quantitative system, it would seem to be wisest, 

 and the part of moderation, to be conservative in the matter of 

 systematic typal adjectives, and to bestow them only in the 

 case of the more unusual magmas, the less common combina- 

 tions of mode and textures (which may conveniently be called 

 motexes), or when redescribing in terms of the new classification 

 some well-known rock which is commonly recognized as ade- 

 quately representative of some usual motex (combination of 

 mode and texture). In other cases it may be suggested that 

 such a simple, substantival form, without the suffix -al, be 

 employed as is clone here, admittedly in a provisional way and 

 with but a limited and local application. In certain cases, of 

 course, these provisional type designations may eventually be 

 rendered entirely systematic and definitive by the addition to 

 the locality root of the suffix -al, if the rock described proves 

 to be worthy of this distinction. 



Camptonose {feldspar-basalt), Castellfullit type. 



Megascopic characters. — Color, medium to dark gray: tex- 

 ture, phanerocrystalline, fine-grained, porphyritic, perpatic : 

 phenocrysts, 5 per cent or less of the rock volume, 1 to 3 mm long, 

 of black or dark green augite and yellow olivine: groundmass, 

 very fine-grained, but many very minute, white tables, evi- 

 dently of feldspar, and black grains, evident with the hand 

 lens. Some specimens, on weathering, show a mottled surface 

 of patches of light and dark gray. 



Microscopic characters. — Minerals present, labradorite, aug- 

 ite, olivine, and ores. The labradorite, of the average composi- 



