246 HENRY S. IVASHINGTOA 



as have been noticed previously. A very few flakes of alkali 

 feldspar are also met with. 



Leucite-tephrite. — -One specimen of this rock was collected at 

 Mte. San. Antonio (707 meters high), which forms one of the 

 girdle of hills around the plain and lies due north of Mte. Lat- 

 tani. The rock shows a fine grained gray groundmass in which, 

 with the exception of very rare augites, the only phenocrysts 

 visible are leucites. These are extremely abundant, making up 

 a large portion of the rock. They are apparently fresh, with a 

 waxy luster ; the smaller ones pale gray, while the larger show a 

 core of dark gray and an outer shell of light gray. This rock is 

 extremely tough. In thin sections the large leucites are very 

 prominent. They are clear and show strong double refraction. 

 Inclusions are abundant, of small crystals of anorthite and green 

 augite. They include also many small slender needles of diop- 

 side, minute grains of magnetite and spots of glass, which are 

 very commonly clustered toward the center of the crystal, thus 

 accounting for the dark gray cores. Beside the leucites only one 

 or two dark green augite phenocrysts were seen in the slides. The 

 groundmass is composed largely of irregularly shaped greenish 

 yellow augite grains, a few small leucites, considerable magnetite, 

 many small crystals of a plagioclase which is shown by its 

 extinction angles to be anorthite, and some small flakes and laths 

 of alkali feldspar. A little residual glass is also present. 



A peculiar leucite-tephrite is that, from what appeared to be 

 a small flow on the road to Conca, below Orchi. It is very dark 

 gray and fine grained, but rather rough in texture. A few pheno- 

 crysts of augite and leucite are visible. Under the microscope 

 it shows the doleritic structure which is so common to the Italian 

 leucite-tephrites. None of the phenocrysts were met with in the 

 single section which was made of this rock. In the groundmass 

 stout columnar, pale green augites are very abundant, the largest 

 showing cores of darker green ; while these are clear and contain 

 few inclusions (of magnetite and glass), their outlines are very 

 irregular, most of the prisms showing deep embayments due to 

 corrosion. A little brown barkevikitic amphibole and a few 



