204 Recent Publications. 
presentation of stanniferous mining in America, excepting perli;ii>s some 
preliminary announcements of the same by Prof. Carpenter before the 
Am. Inst, of Mining Engineers. 
The metalliferous deposits of the Black Hills belong to many different 
classes, none of which he regards true fissure veins. The gold deposits 
are primarily of the Archaian age and yield mainly an auriferous pyrite. 
Sometimes the lodes are of lenticular shape, forming iadependent mem- 
bers of the slate and schist series, and share in all their folds and contor- 
tions, having a columnar cleavage like them coincident with the bedding. 
From these have been produced placer deposits both of tin and gold. Some 
of these^are of the age of the Potsdam and some are Quaternary. The' 
latter yield yet some gold, but their richer parts, like the Deadwood gulch,, 
are practically exhausted. The existence of gold in the Potsdam placer 
proves that the Archtiiau was auriferous when it was submerged by the 
encroaching Potsdam sea. The subsequent laccolitic intrusion of felsite, 
below the Potsdam in some places and above it in others, corresponding tf> 
the laccolites of trachyte and other acid eruptives such as those described 
by Mr. Gilbert in the Henry mountains, is another instance in which the 
acid eruptive was not able for some reason to reach the surface, and is 
perfectly comparable, both in age and lithology to some of the felsytes 
found on the north shore of lake Superior.* The rock was gold-bearing 
before the advent of the porphyry. Its effect seems to have been to con- 
centrate the gold and to render it more free-milling. 
The tin deposits were discovered in 1877 by professor Richard Pearce,. 
f j'om samples of black sand sent to him from the Black Hills. He found 
it to be cassiterite. Since then the known area of tin ore has been constantly 
expanding, but principally since 18S3 under the instigation of major A.J. 
Simmons who employed Prof. W. P. Blake to investigate the find.f Tin 
is now found throughout the area surrounding Harney's peak, and in the 
granite areas extending south and west of Custer City, as well as in the 
small Archtcan area west of Deadwood, a pai-t of which extends into Wyom- 
ing. Gold and tin associated in pyrite, are here found in veins of coarse 
granite. These are not intrusive but segregated veins lens-shaped and 
parallel with the bedding of the schists. 
EEOENT PUBLICATIONS. 
1. State and Oovernmeni reports. 
Royal society of Canada, Proceedings and Transactions, vol. v, contains, 
with other papers, the following: On a specimen of Canada native 
platinum from British Columbia, by Hoffmann ; Microscopic petrography 
of the drift of central Ontario, by Coleman; The faults and foldings of 
the Pictou coal field; Note on fossil woods and other plant remains, from 
the Cretaceous and Laramie formations of the western territories of 
♦Compare: Some tliougbts on eruptive rocks, vritb special reference to those of 
Minnesota. N. H. Wincbell. Proc.;A. A. A. S. Cleveland. ISSS. 
tAm. Jour. Sci. Sep. 1S83. 
