REVIEWS 607 
ordinary type.’ The report discusses the general geology, the ore-deposits 
and their minerals, with description of one new species, Coronadite. There 
is also an extended discussion of metasomatic processes, and finally a 
description of the mines and mineral-deposits. 
CoWiEW.. 
Slate Deposits and Slate Industry oj the United States. By T. NELSON 
DALE. With sections by E. C. Eckert, W. F. HILLEBRAND, 
and A. T. Coons. (U.S. Geological Survey, Bulletin No. 275.) 
Pp. 154, 25 plates. Washington, D.C. 
The phenomena of slate are described and explained. The sedimen- 
tary slates are classified in two divisions: clay slates and mica slates; and 
the latter division, which includes all commercial slates, is subdivided into: 
(1) fading and (2) unfading, according to the presence or absence of suffi- 
cient FeCO, to produce discoloration on weathering. Further subdivision 
is into: (a) graphitic slate, (b) hematitic (reddish), (c) chloritic (greenish), 
(d) hematitic and chloritic (purplish). The slates of fifteen states are 
described. Merriam’s tests for strength, toughness, density, softness, 
porosity, and corrodibility are given for a number of slates, and the com- 
parative characteristics discussed. The slate production of the United 
States in 1903 was $6,256,885; in 1904 it was $5,617,195. 
C. W. W. 
A Preliminary Reconnaissance of the Mancayan-Suyoc Mineral 
Region, Lepanto, P. I. By A. J. EvELAND. (Bulletin No. 4, 
The Mining Bureau, Manila, P. I., 1905. Pp. 58, 42 plates.) 
The rocks of this region consist of schists and dioritic rocks of unknown 
age, Eocene limestone and conglomerate, and volcanics. The ores carry 
both gold and copper, but are developed only in the most primitive way. 
C. W. W. 
The Coal Deposits of Batan Island, with Notes on the General and 
Economic Geology of the Adjacent Region. By WARREN D. 
SmitH. (Bulletin No. 5, The Mining Bureau, Manila, P. L, 
TOO549 bp.)50, 20 plates.) 
The general region is volcanic and of recent age. Batan, however, is 
composed largely of folded sedimentaries ranging in age from Eocene to 
Pleistocene, and resting on pre-Tertiary dolerite and other rocks. There 
are eleven coal seams of which two are generally workable. The coal is 
good steam coal. C.W. W. 
