536 THE AMERICAN NATURALIST. [Vou. XXXII. 
up to within a few years past. Osann and Hlawatsch ? now report 
the existence of blocks of a porphyritic rock in the Viezzena valley, 
in whose hand-specimens ‘phenocrysts of sanidine are plainly evident. 
In the thin section, phenocrysts of orthoclase, microcline, plagioclase, 
pyroxene, hornblende, mica, and garnet are in a holocrystalline 
groundmass composed of feldspars, nepheline, sodalite, and various 
secondary products. The authors call the rock a nepheline-syenite 
porphyry. It differs from the original of the liebenerite-porphyry in 
containing no nepheline phenocrysts. 
On the contact of a hauynophyre dike with limestone near Horberich, 
in the Kaiserstuhl, Brauns ° finds a contact rock that is very unusual 
in composition. It consists of melanite, calcite, augite, gehlenite, 
hauyn, apatite, and mica. The gehlenite is in well-defined crystals, 
intergrown with the calcite, garnet, and the hauyn. The hauyn, 
melanite, and augite are thought to have been derived from the 
volcanic rock, and the gehlenite to be a result of the contact action. 
A few volcanic rocks from the Baluchistan-Afghanistan boundary 
have been submitted to McMahon ° for study. He finds among them 
andesites, basalts, a granite, a quartz-syenite, various acid lavas, 
pumice, tuffs, and a few sedimentary rocks. The phenocrysts in the 
andesite are oligoclase and andesine, the former predominating. 
Three of the andesites contain anthophyllite; and one, an augite 
hornblende-andesite, contains phenocrysts of olivine. 
The lava* of Mt. Edgecombe, Krusov Island, Alaska, is an hyper- 
sthene-andesite composed of two generations each of plagioclase, 
hypersthene, augite, and magnetite. 
Cross °* reports the existence of another volcanic rock containing 
analcite. The rocks form a small outcrop in “The Basin,” about 
twelve miles west of Cripple Creek, Colo. It is a basalt, composed 
of the usual constituents of basalt, to which are added large and small 
colorless grains of analcite. Analysis of the separated analcite yielded: 
SiO, AlO, FeO, FeO CaO SrO MgO KO NaO K,O_ Tot. 
51-24 24.06 1.20 102. 00. j3. tag 13.61 . 9.09 = 10042 
The analysis of the rock shows it to be very closely allied to the 
monchiquites of Rosenbusch. 
1 Min. u. Petrog. Mitth., vol. xvii, p. 556. 
2 Bericht. Oberhess. Ges. f. Natur. u. Heilk., 1808. 
3 Quar. Journ. of Geol. Soc., p. 289, August, 1897. 
* Cushing, H. P. Amer. Geol., I i September, 1897. 
5 Journ. of Geol., vol. v, p. 684, 
