Washington — Catalan Volcanoes and their Rocks. 239 



Of the salic minerals a plagioclase of about the composition 

 Ab 1 An 1 is the most common, though it is quite wanting in 

 some of the rocks. Alkali feldspar seems to be rare, though 

 its presence in some amount is demanded by the chemical 

 composition. It would seem that, in most cases, the condi- 

 tions did not permit of its crystallization, and that it solidified 

 as a glass. Nephelite, sometimes in almost euhedral crystals 

 but usually as an ill-defined base, is more common, but this, 

 too, is prone to solidify as a glass. The other prominent salic 

 minerals, quartz, leucite, and the socialites, are not found in 

 these rocks. 



Chemical characters. — The chemical features of the Catalan 

 rocks are shown by the analyses in the table annexed, all of 

 which were made by the writer. Considering the small size of 

 the district, and the general uniformity in the mineralogical 

 and textural features, they would seem to be sufficiently numer- 

 ous to convey a just idea of the true relations. 





I 



II 



Ill 



IV 



V 



VI 



VII 



SiO„... 



47'66 



44*55 



43-64 



44-29 



44-20 



44-82 



44-80 



A1 2 3 - 



14-36 



12-48 



13-12 



12-62 



13-96 



1406 



15-51 



Fe 2 3 . 



2-83 



2-81 



6-40 



3-61 



3-19 



4-56 



2-35 



FeO .. 



8-44 



8-54 



5-52 



8-84 



8-41 



7-27 



8-52 



MgO .. 



8-19 



10-85 



9-36 



10-06 



8-03 



8-60 



8-83 



CaO... 



9-36 



7-99 



9-52 



9-23 



9-79 



9-56 



9-91 



Na 2 0_. 



3-51 



4-04 



, 3-89 



3-25 



3-66 



3-69 



2-99 



K 2 0... 



1-54 



2-57 



2-18 



1-82 



2-35 



2-30 



2-29 



H„0 + _ 



0-17 



0-56 



0-49 



0-21 



0-76 



0-30 



0-16 



h;o-.. 



0-20 



0-18 



0-16 



0-09 



0-12 



0-05 



0-09 



co„... 



none 



none 



none 



none 



none 



none 



none 



Tid„ .. 



3-83 



4-32 



4-55 



4-92 



4-10 



4-25 



4-01 



ZrCT... 



n.d. 



n.d. 



n.d. 



0-02 



n.d. 



n.d. 



n.d. 



P.O.— 



0-45 



0-70 



0-74 



0-57 



0-62 



0-67 



0-68 



so,.... 



n.d. 



0-05 



n.d. 



0-05 



n.d. 



n.d. 



n.d. 



MnO .. 



n.d. 



n.d. 



n.d. 



n.d. 



0-51 



none 



0-08 



NiO. __ 



n.d. 



n.d. 



n.d. 



n.d. 



0-14 



n.d. 



0.13 



BaO... 



n.d. 



n.d. 



n.d. 



0-06 



n.d. 



n.d. 



n.d. 



SrO . . . 



n.d. 



n.d. 



0-03 



0-04 



n.d. 



n.d. 



n.d. 



100-54 99-64 99-60 99'68 99'84 100-13 100-35 



Subrang III.5.3.4 III.6.2.4 III.6.2.4 III.6.3.4 III.6.3.4 III.6.3.4 III.6.3.4 



I. Camptonose (feldspar-basalt). Upper Flow, Castellfullit, 



near Olot. 

 II. Monchiquose (nephelite-basanite). Below Chapel Sant 

 Medir, Llora, near Gerona. 

 IIL Monchiquose (nephelite-basanite). La Garrinada, Olot. 

 IV. Limburgose (nephelite-basanite). Las Planas, South of 

 Olot. 

 V. Limburgose (nephelite-basanite). Cruzcat, South of Olot. 

 VI. Limburgose (nephelite-basanite), Montsacopa, Olot. 

 VII. Limburgose (limburgite). Fuente San Roque, Olot. 



