378 Tlie AmericciJi Geologist. December, i898 
the dunyte and gneiss. The author's conclusion, which appears to 
be well sustained by the facts, is that the corundum is not in any sense 
a secondary mineral, but dates from the original solidification of the 
dunyte, having existed in solution in the molten mass of the dunyte 
at the time of its intrusion and separated out among the first minerals 
as the mass began to cool. The dunyte magma, holding in solution 
the chemical elements of the different minerals, would be like a sat- 
urated liquid, and as it began to cool the minerals would crystallize 
out, not according to their infusibility. but according to their solubility 
in the molten magma. The more basic portions, according to the 
general law of cooling and crystallizing magmas, being the most in- 
soluble, would be the first to separate out. These would be the 
oxides containing no silica, such as chromite, spinel and corundum. 
The important experiments of Morozewicz with molten basic glasses 
are cited as fully corroborating this view; and it is noted that the 
crystallization of the corundum and other oxides would begin on the 
outer border of the mass where cooling was most rapid. Convection 
currents would then tend to bring new supplies of material carrying 
alufnina into this outer zone, where it would be deposited as corun- 
dum. This is essentially Becker's theory of fractional crystallization: 
and it is noted that the high fluidity of these very basic magmas is a 
very favorable condition. w. o. c. 
Erionite, a new Zeolite. By Arthur S. Eakle. {Ai/i.J. Set., Jj6, 
66-68.) 
This mineral occurs as very fine, white, pearly and woolly threads, 
associated with opal in a rhyolyte-tuff from Durkee, Oregon. Analy- 
sis gives: SiOs, 57.16; AUO3, 16.08; CaO, 3.50; MgO, 0.66; K2O, 3.51; 
Na20, 2.47; H2O, 17.30; total, 100.68. Allowing one molecule of 
water as hydroxy!, as the hydration experiments indicate we obtain 
the formula H2 Sie AI2 Ca K2 Naz Oit + 5H2O. This is analogous 
to the formula for stilbite with the calcium largely replaced by alka- 
lies; but in other respects the new zeolite has no resemblance to stil- 
bite. The name refers to its woolly appearance. An analysis of the 
associated milky opal gave: SiOs, 95.56; H2O, 4.14; and a trace of alum- 
ina, w. o. c. 
Metotnorphistn of Rocks and Rock Flouiage. By 0. R. Van Hise. 
[Am. J. Sci., i§6, 75-gi ; Bull. Geol. Soc. A?n., g, 26g-j28.) 
This important contribution to dynamical geology, which is con- 
densed from a partly written treatise on metamorphism and the meta- 
morphic rocks, is mainly a physical study; but the important coopera- 
tion of chemical agencies is fully recognized in the paragraphs on 
chemical action and its relations to heat and pressure, the upper and 
lower physico-chemical zones, etc. Vant Hoff's law that "on the 
whole, the preponderating chemical reactions at lower temperatures 
are the combinings (associations) which take place with the develop- 
ment of heat; while the reactions preponderating at higher tempera- 
tures are the cleavings (dissociations), which take place with the ab- 
