ITALIAX PETROLOGICAL SKETCHES 56 1 



sanidinc occur in wcll-fonncd cr^'stals, along with biotite, mag- 

 netite and apatite. A little haiiyne occurs, but augite is not 

 spoken of as present in the groundmass. There is unfortunately 

 no analysis of this rock. Klein describes also two rocks which 

 nia\- belong here, one from La Canonica and one from Proceno. 

 The former is apparently a transition type towards the leucitites, 

 the latter is noteworthy as containing haiiyne and also a very 

 basic plagioclase. Its high percentage of silica and low lime 

 and magnesia are also remarkable (anal. 10, page 565). 



The "leucitophyr" of vom Rath' is probabl)^ a leucite-phono- 

 lite since he mentions a colorless weakly refracting mineral as 

 the last jM'oduct of crystallization. He thinks this may be feld- 

 spar but it answers to the characters of nepheline. All of the 

 leucitic-trachytes as well as some of the leucitophyrs, described 

 by Bucca, probably belong here. This is shown by their augite 

 being pleochroic, the frequent presence of haiiyne, and the pres- 

 ence in the groundmass of a "colorless glassy base," rich in 

 soda and easily gelatinizable {^op. cit., p. 19). 



I may add that a specimen from Acquapendente in the col- 

 lection of Yale University closely resembles my specimen, gives 

 abundant gelatinous silica with acids, and is apparently identical 

 with one from that locality described by Bucca. According to 

 Scrope,' and apparently also according to Ricciardi^ the lavas of 

 Ac(|uapendente are connected with the volcanic center of Radi- 

 cofani to the north. 



Leucite- trachyte proper is not definitely known from this 

 region, though possibly one or two of Bucca's rocks belong 

 here. 



Lciicite-tcpJirite. — Rocks belonging to this group are very 

 abundant, and transition forms to the other types are common. 

 Of my specimens only a few will be described in detail, as 

 Klein's descriptions cover the ground very full}'. The rocks of 

 this group are generally of quite basaltic appearance, and resem- 



■ VoM R.'VTH, op. cit., 290. 



^SCROPE, Volcanoes, London, 1862, 354. 



^RicciAKDi, Terreni Vulcanici, Florence, 1879, 133. 



