378 REVIEWS 
considered. One hundred and seventy-one samples were collected, and 
the results of the tests applied in the government laboratories are given. 
The best materials in each county are described, and the many figures 
and plates are maps indicating the places where good material is found 
and where the samples were collected. Practically all the samples tested 
were of igneous rocks, mainly basalts, and it is upon these that the 
state will largely rely for its road material. 
ACO 
Geology and Ore Deposits of the Blewett Mining District. By 
CHARLES E. WEAVER. Wash. Geol. Survey Bull. 6. 1911. 
Pp i 1OAe font plsiaro, 
This small gold camp lies in central Washington. The region is one 
of a few Carboniferous (?) and Tertiary sedimentary formations that 
are dislocated and metamorphosed by several large igneous intrusions. 
Gold-bearing fissure veins cut a peridotite mass that shows considerable 
differentiation, and which is now largely altered to serpentine. The 
gangue minerals are principally quartz and calcite with which are 
associated pyrite, arsenopyrite, and native gold. Considerable talc is 
found in the vein walls. It is supposed that the mineralization was 
related to the intrusion of granodiorite, and it is possible that the ser- 
pentinization of the peridotite took place at the same time. The 
earlier workings were in the oxidized zone, and the ores were free milling, 
but since the sulphide zone has been reached most of the ores are treated 
by the cyanide process. The district was first exploited because of its 
placer deposits. 
AY Eee 
Geology of the Berners Bay Region, Alaska. By ADOLPH KNOPF. 
U.S. Geol. Survey Bull. 446. 1911. Pp. 55; figs. 4; maps 2. 
The Berners Bay region forms the northwestern extremity of the 
long zone of auriferous mineralization known as the Juneau gold belt. 
The rocks consists of sedimentary slates and graywackes of Jurassic or 
Lower Cretaceous age, metabasalts, quartz diorite-gneiss, diorite, horn- 
blendite, and felsitic or rhyolitic dikes and sills. 
The important ore bodies are largely in the diorite, and are in the 
form of fissure veins, stockworks, and stringer lodes. The gold occurs 
in the native state, associated with quartz and pyrite, and lesser amounts 
of other sulphides and gangue minerals, the resulting ores being usually 
of a low grade. Descriptions of all the mines are given. 
Ave 
