REVIEWS 491 
Cobalt-nickel Arsenides and Silver Deposits of Temiskaming. (3d 
ed.) By Witter G. Miter. Report of the Bureau of Mines, 
ToO7e = Vole Vil -Part i212) pp. 4 maps, and ‘10°: illus- 
trations. ‘Toronto, 1908. 
This report brings the mining situation of the region clearly before the 
public. Conditions have adjusted themselves to a working basis and stock- 
jobbing has almost ceased. The oldest rocks of the area are the Keewatin 
into which is intruded the Laurentian granite. Unconformably on these is 
the Lower Huronian conglomerate and slates. The Middle Huronian lies 
unconformably on the Lower. Finally there was a large intrusion and 
extrusion of basic rocks in Keeweenawan time. Associated with the diabase 
and on its outer edge are the ore-bearing veins. Occasionally they are 
found running out into the Keewatin green-schists. The width given for 
the veins is 14 inches or less. At Silver Islet they have been worked to a 
depth of 1,200 ft. 
The ores present are: native silver, smaltite, cobaltite, niccolite, chloan- 
thite, millerite, argentite, pyrargyrite, proustite, dyscrasite, native bismuth, 
tetrahedrite, chalcopyrite, bornite, mispickel, pyrite, galena, asbolite, and 
zinc blende. The following occur in the oxidized zone: native silver, ery- 
thrite, and annabergite. Native silver and smaltite are the important ones. 
The origin of the ores is still unknown. The total value of ore produced up 
to 1908 was $10,000,000, of which 50 per cent. was profit. 
The report contains descriptions of the most important mines also an 
appendix giving a list of companies incorporated during 1904-8, and an 
early history of the cobalt industry in Saxony. Caen 
Some Relations of Paleogeography to Ore Deposition in the Missis- 
sippi Valley. By H. Foster Barn. Mexico, 1907. 
The ore deposits are chiefly lead and zinc which are in no way related 
to vulcanism. The Wisconsin district is considered in detail. The present 
ore bodies are believed to be the result of reduction of sulphates to sulphides 
by reactions between ore-bearing solutions and organic matter in the country 
rock. Sulphurization of carbonates has also taken place. Original pre- 
cipitation of the material from the sea water was likely due to the same 
reactions. Original localization may have been due to: (1) local abundance 
of th: metals in solution; (2) local abundance of the organic reducing 
matter; (3) locally peculiar organic matter leading to particular efficiency 
in producing deposition. 
The local abundance of lead and zinc in solution may have accumulated 
