PETROLOGICAL ABSTRACTS AND REVIEWS 497 



Lacroix, a. "Les roches grenues d'xin magma leucitique etudiees 

 a 1 'aide des blocs holocristallins de la Somma, ' ' Comptes Ren- 

 dus, CLXV (19 1 7), 205-11. 



Ottajanites are leucite-tephrites having the chemical but not the mineralog- 

 ical composition of sommaites. They are microHtic and contain leucite and 

 plagioclase. Vesuvites are the leucite-tephrites of Vesuvius. These are 

 described in more detail in a later publication (see next abstract). Puglianites 

 are coarse-grained rocks composed of automorphic augite in a groundmass of 

 leucite and anorthite. Certain varieties contain a little biotite, hornblende, 

 and orthoclase. Sehastianites are like the puglianites chemically but are 

 different mineralogically. They are composed of more or less automorphic 

 anorthite, with a little augite, apatite, and biotite. Leucite is absent, all 

 the potash being in the biotite. Chemical analyses but no modal percentages 

 are given. 



Lacroix, a. "Les formes grenues du magma leucitique du volcan 

 laziale," Comptes Rendus, CLXV (1917), 1029-34. 



Braccianite is appUed to certain leucitites from the Lake of Bracciano but 

 why given a new name is not clear, except to distinguish them from the Capo 

 di Bove leucitites. 



Lacroix, A. " Dacites et dacitoides, a propos des laves de la Mar- 

 tinique," Comptes Rendus, CLXVIII (1919), 297-302. 

 According to Lacroix, petrographers classify as dacite only those quartz- 

 bearing andesites which have phenocrysts of quartz; those having quartz in 

 the groundmasses or hidden in glassy groundmasses, and therefore only shown 

 chemically, he says are called andesites. The latter rocks he would caU 

 dacitoides. He would extend the term to cover, not only the extrusive equiv- 

 alents of the quartz-diorites, but also quartz-gabbros, in that he would have 

 oligoclase-, andesine-, and labradorite-dacitoides, to the fvirther confusion of 

 present nomenclature. (H. S. Washington, Amer. Jour. Sci., L [1920], 456, 

 objects to these terms and uses Rosenbusch's term hyalodacite.) 



Lacroix, A. "La constitution mineralogique et chimique des laves 

 des volcans du Tibesti," Comptes Rendus, CLXIX (1919), 

 169-75. 

 In this paper basanito'ides is proposed for basanites in which the nephelite 



is not crystallized but remains "potential in the glass." Chemically they are 



basanites. 



