Personal and Scientific News . 
339 
great dimensions, always contains some gold and may under certain 
favorable circumstances contain enough of the latter metal to be treated 
as an ore. The bulk of the gold is nearly always in the quartz filling 
the open fissures. 
Mr. Fairbanks, while admitting that some veins may have been 
formed in open fissures, thinks that the process in most cases began by 
a crushed zone and that the vein matter was deposited as the solutions 
removed the crushed material, leaving at no time large empty spaces ; 
great stress is laid upon the removal of material and the substitution by 
silica. According to my view no material has been “ removed ” bodily 
(excepting, of course, easily soluble rocks like limestone); there has 
only been an interchange of substance, a replacement of the rock form¬ 
ing minerals by carbonates, sericite and pyrite. The shape of the frag¬ 
ments, even their sharp edges, has often been preserved, only the 
composition changed. It is not denied that silica may have replaced 
certain minerals, but this process appears to me of very subordinate 
importance. Silicification of the wall rocks of the California gold-quartz 
veins has often enough been asserted ; but as far as I know, not proved 
by chemical and microscopical investigation. 
An absence of typical comb-structure does not prove the absence of 
open fissures. This comb-structure is frequently observed, but the 
“ ribbon-structure ” is more common. This latter may be of different 
origin; it may be caused by successive additions in open fissure through 
a long period of time ; it may also be formed by additions to the vein 
on the outside by successive opening and tightening of the walls ( loc . 
cit ., p. 155); it has also in many cases its origin in a dislocation and 
sheeting of the quartz vein subsequent to the filling. 
Thus, in conclusion, I believe that the two processes — filling of open 
spaces chiefly by quartz and replacement of the country rock chiefly by 
carbonates and sericite—have proceeded simultaneously and are both 
of great importance. In the California gold-quartz veins the former 
process is accentuated because the richest ores have usually been 
formed by it. In other regions the filling of open spaces may be entirely 
subordinate, and the results of the replacement of the most economic 
importance. Waldemar Lindgren. 
PERSONAL AND SCIENTIFIC NEWS. 
Mr. Warren Upham is contributing a series of articles on 
the “Physical Features of Minnesota and the Northwest ” to 
the Northwest Weather and Crops. 
A Congress of mining and geology will be held at Budapest 
on Sept. 25tla and 26th, in connection with the Hungarian 
Millennial Exhibition which opens May 2nd. 
Tyndall’s “Glaciers of the alps”, first published nearly 
thirty-six years ago and for a long time out of print, has been 
reprinted by Longmans, Green and Co. of London. 
Mr. Harry Landes, professor of geology, mineralogy and 
mining in the State University of Washington, at Seattle, has 
