No. 382.] REVIEWS OF RECENT LITERATURE. 813 
twinning lamelle produced along slipping planes parallel to the 
rhombohedron. In addition to the minerals above mentioned there 
are also present in the rock in small quantity allanite, anatase, 
brookite, ilmenite, zircon, an inclusive of sodalite in one of the 
quartz phenocrysts, some fluorite and barite. The analysis following 
shows the presence also of some other substances not detected by 
the microscope. 
SiO, AlO; Fe,03 FeO Fe K,O Na,O CaO MgO BaO Cu Pb SO; S BO,O3 TiO, PO; Cl F H,O 
68.89 14.05 2.18 1.43 .23 4.30 4.56 2.15 .83 .58 03.04 .30.26 .38 23 .03 .07 .05 .41 = 
101.00 
The ores of the district are mainly magnetite, mixed with small 
quantities of pyrite, hematite, limonite, chalcopyrite, malachite, and 
cuprite, and associated with tourmaline, calcite, apatite, and the 
fresh and altered constituents of diorite. They are thought to be 
differentiation products of the diorite, while the associated minerals 
are the result of later dynamic and pneumatolytic processes. 
Swiss Schists. — In the course of a study of the geology of the 
Val di’ Mortirolo in the Alps, Salomon! met with several rocks 
of sufficient interest to merit detailed investigation. These are 
adamellites, hornblende-diorites, potassium and sodium gneisses, and 
micaschists, exhibiting in a very clear manner the effects of moun- 
tain-making forces. These effects are expressed in different ways, 
according to the nature of the rock acted upon, either as bending, 
as crushing, or in chemical transformations. The adamellite has 
yielded a “microcline-augen-gneiss,” and the hornblende-diorite a 
clinozoisite-albite-amphibolite. After examining critically the effect 
of the mountain-making forces in deforming the mineral components 
of the rocks studied, the author concludes that the bending of great 
(rock) masses without fracture hardly ever occurs, but that fracture- 
less bending and deformation with fracture may unite in different 
Proportions, depending upon the mineral composition of the rock 
effected, the severity of the pressure and the duration of its action, 
to produce rock-bending. A special form of fractureless deformation 
is effected through the chemical transformation of minerals and the 
consequent transportation of their material particle by particle. 
This view of dynamical metamorphism is not very different from 
that of Van Hise, as discussed in the article referred to below. 
1 Neues Jahrb. f. Min., etc., Bd. xi, p. 355- 
