338 The American Geologist. May, 1896 
CORRESPONDENCE. 
The Gold-Quartz Veins of California. In the March number of 
the American Geologist, Mr. H. W. Fairbanks gives an interesting 
description of the gold veins of Inyo county and adjacent parts of 
eastern California. In this paper references are made to an article on 
the "Characteristic Features of the California Gold-Quartz Veins" 
which I published last year in the Bulletin of the Geological Society of 
America. As some of these references do not fairly represent my 
views, giving for instance the impression that no such process as re- 
placement was recognized, only a filling of open fissures, it may be per- 
missible to briefly indicate the manner in which I believe these deposits 
have been formed. 
On page 153 Mr. Fairbanks finds that the conclusions reached in my 
paper do not at all apply to eastern California, citing especially the 
abundant occurrence of quartz veins in granitic rocks in that region. 
On the first and second pages of my paper I have, however, expressly 
excepted the deposits of Mono, Inyo and San Bernardino counties from 
the discussion, stating that they differ more or less from the normal 
type on the western slope. The following statements also only apply to 
the normal gold-quartz veins of the western slope of the Sierra Nevada. 
The deposits are in all cases found along fractures and fissures which 
have a greatly differing character in different rocks and districts. In 
some cases there was only a crushed zone with extremely small inter- 
stitial spaces : again there may have been a crushed zone with larger 
openings between the fragments : or there may have been sharp, clear 
cut fissures often producing open spaces supported at frequent intervals 
by the closing walls. A fracture may change its character from an open 
fissure to a crushed zone in a comparatively short distance. These open 
spaces were seldom of great width, five feet being a rarely occurring 
measure. It is very probable, as Mr. Fairbanks remarks, that move- 
ment has frequently taken place along many fissures during the filling, 
and in such manner successive spaces opened for deposition. Along the 
mother lode some exceptionally heavy bodies of quartz occur, but to 
cite such dimensions as " fissures five to twenty feet wide and hundreds 
of feet in extent " (loo. cit., p. 156) as representing California quartz 
veins is very far from the mark. There is nothing very improbable in 
the existence of open spaces at considerable depth ; the way in which 
stopes in the deepest mines, in hard rock, often stand without support 
shows this plainly. There is of course a limit and below, say 10,000 feet, 
the open spaces are probably very small. 
The solutions circulating in these fissures deposited silica, gold and 
metallic ores in the open spaces : simultaneously an active process of 
metasomatic replacement went on in the partly loosened and crushed 
country rock adjoining the fissures, by which it was transformed to a 
mixture of carbonates, sericite and iron-pyrites : usually all three of 
these minerals are present. Only in certain black, carbonaceous slates 
the former two are often lacking. This zone of altered rock is often of 
