1894.] Petrography. 1021 
of magnetite in a matrix of oligoclase. The structure of the spheroids, 
with the younger minerals nucleally and the older ones peripherally 
distributed, indicates to the author that they were produced by liqua- 
tion processes. The rock from Balungstrand possesses a coarse ground- 
mass consisting almost exclusively of microcline and quartz. The 
spheroids are essentially oligoclase spherulites peripherally enriched by 
biotite. They are clearly older than the groundmass. 
Diabase and Bostonite from New York.—A few dyke rocks 
cutting the gneisses of Lynn Mountain, near Chateaugay Lake, Clin- 
ton Co., N. Y., are described by Eakle’ as consisting of olivine diabase’ 
and of bostonite. The latter rock is porphyritie with phenocrysts of 
red orthoclase in a fine-grained groundmass with the trachytic struct- 
ure. It differs from the other bostonites of the region in the presence 
of much chloritized augite in its groundmass. It is also more acid 
than these. Its analysis gave: 
SiO, AlO, FeO, CaO MgO K,O Na,O Loss Total 
67.16 1453 417 136 41 610 5.55 1.10 = 100.28 
The olivine diabase differs from the ordinary ophitic diabases in that 
much of its augite is in idiomorphic forms. They thus resemble Kemp’s 
augite camptonites. 
Petrographical News.—A very interesting series of analyses of 
rocks from the central and northeastern portions of the Mittelgebirge is 
given by Hibsch? The series includes analyses of phonolites, doler- 
ites, camptonites, nepheline and leucite tephrites, augitites and basan- 
ites. Many of the rocks have been described in the literature. 
Cohen’ has obtained from the Transvaal, Africa, specimens of a cal- 
cite bearing aplite and of a melilite augite rock of a somewhat abnor- 
mal character. The aplite is from the mine of the Iron Crown Gold 
Mining Co., near Hamertsburg, and the melilite rock from near Pala- 
bora. The melilite rock is a fine-grained aggregate composed largely 
of honey-yellow melilites and black augites. On its druse walls are 
little crystals of the first-named mineral, and through the druse cavi- 
ties extend thin plates of copper. In the thin section, clear, colorless 
melilites, with rounded outlines and olive-green grains of augite are 
seen to lie in an opaque granular groundmass in which are dots and 
flakes of copper. 
T Amer. Geologist, xii, p. 31. 
* Min. u. Petrog. Mitth., xiv, p. 95. 
? Minn. u. Petrog. Mitth., xiv, p. 188. 
