606 The American Naturalist. [July, 
The Basalts of Kloch in Steiermark.—The main portions of 
the Kléch Mountain mass are basalts and their tuffs. Sigmund’ de- 
scribes these and the other rocks in their vicinity as nepheline basan- 
ites, palagonite tuffs, nephelinites and nepheline basalts. 
All the augites in the basanites have the “ hourglass form,” and all 
the feldspars are bytomites. The augites are also zonal with a color- 
less nucleus and a violet-gray peripheral portion. The extinction of 
the nucleus is higher than that of the surrounding portion, and the ex- 
tinction in the pyramidal zone of growth (Anwachs-Kegel) greater 
than that in the prismatic zone. The nephelinite of the Hochstraden 
contains two augites. The larger consists of colorless nuclei and green- 
ish-yellow peripheral zones, while the smaller ones are composed entirely 
of the greenish-yellow material. Hauyn is an essential component of 
the groundmass. In some specimens it occurs in as large quantity as 
the nepheline. An analysis of this rock gave: 
SiO Tio. AlO3; FeO; MnO MgO CaO NaO KO POs SOs Cl. Loss Total 
16.50 10.62 3.29 12.63 5.95 2.36 .89 64 .36 2.63 = 99.62 
The basalt of Kléch and the nephelinite of the Hochstraden are 
thought to have been produced by the differentiation of one magma. 
The Volcanic Rocks near Bensen, Bohemia.—Hibsch,’ in 
his description of the Bensen sheet of the Bohemian Mittelgebirge, 
gives brief accounts of the basalts, augitites, tephrites, basanites, phono- 
lites and trachytes occurring as lavas and tuffs, and of the camptonitic, 
trachyte-andesitic and tinguaitie dykes so common in the district. The 
basalts, which are the oldest lavas, form stocks, sheets and dykes; the 
tephrites, which are the next older, occur in sheets and as tuffs, and 
the phonolites and trachytes as bosses. The tinguaite dykes are con- 
nected with the phonolitic intrusion at Miihlérzen, but the others are 
more closely connected with the volcanic center at Rongstock. All the 
eruptives are Tertiary or younger. The most interesting of these 
rocks is in the trachyte-andesite dyke. The author describes it under 
the name of gauteite, and regards it as the complementary form to the 
monchiquites. It is a rock of a light color and trachytic habit. In 
composition it differs from bostonite-porphyry in the possession of 
phenocrysts of plagioclase. It consists of large porphyritic crystals of 
hornblende, augite, plagioclase and occasionally biotite in a ground- 
mass composed of the same dark minerals, sanidine and andesine, 
cemented by glass. An analysis yielded: 
ê Min. u. Petrog. Mittheilungen, XV, p. 361 and XVI, p. 337. 
*Ib., B, AVEL, p. 1 
