DESCRIPTION OF THE COLLECTION. 115 
an auriferous vein, but I have not made any examination of the specimen for gold by crushing 
and washing or by chemical tests. 
No. 94. Canada Hill, near Nevada City.—A fragment of ferruginous quartz, stained by the 
decomposition of pyrites, and containing minute grains of gold. The auriferous quartz of 
Canada hill is well known in Nevada as a rich source of gold. "There are numerous other 
quartz veins, or “leads,” in that vicinity, but they are not represented in the collection; this 
specimen being the only one of auriferous quartz that I find from California. 
No. 95. Pueblo creek. —'This, according to the label of Mr. Marcou, is “fer argentifere? en 
filon’? (vein of argentiferousiron.) It is a small mass of quartz, evidently a part of a vein which 
appears to have had the character of a true fissure vein, the quartz having the comb-like struc- 
ture so well known in the mining regions of Cornwall. The metalliferous portion is implanted 
among the ends of the compressed quartz crystals, in a layer transverse to them, and a second 
parallel layer is seen, about one quarter of an inch distant, in the body of the quartz, but which 
was at one time on the inner wall or face of the fissure. It thus appears that there have been 
two successive depositions of the ore, a layer of quartz having taken place in the interval. That 
the inner layer of ore now imbedded in the quartz was once upon its surface is shown conclu- 
sively by the fact that it presents a zigzag line, the angles exactly conforming to the angles 
and terminations of quartz crystals. 
A freshly-fractured surface of the small layer of ore presents a mass of rosettes of beautiful 
red color, formed by an aggregation of small plates. "They are soft, and easily crushed by the 
point of a knife to a red powder resembling that of hematite. It does not give off fumes before 
the blow-pipe, and is infusible. A solution in nitric acid does not give any reaction for silver 
with hydrochloric acid. The fragment heated by the blow-pipe becomes magnetic, and a reac- 
tion for iron is obtained from,the nitric acid solution. The mineral is probably hematite. 
o. 96. From two miles north of Cactus Pass, Aquarius mountains.—This specimen consists of 
quartz, with some feldspar, bearing thin seams and irregular veins of a dark mineral, with a 
metallic lustre. This, on being scratched, gives a dark blood-red streak, like hematite. It is 
infusible before the blow-pipe in the outer flame, but in the inner it fuses to a black magnetic 
globule. It is, therefore, in all probability, hematite, and similar in composition to the speci- 
mens previously described. 
These specimens of peroxide of iron present very different appearances, and, to an ordinary 
observer, would seem to be entirely different in their chemical characters. Hematite is a com- 
mon product of volcanic action, and is found abundantly in the lavas of Vesuvius. It is inter- 
esting to note the number of the specimens from different localities, brought in by Mr. Marcou, 
while the magnetic iron ore, which in the Appalachian chain is the most common and abundant 
crystalline ore, is not represented in the collection. 
o. 9 o label. This specimen probably belongs with some of those 
already described, but has either been displaced, or has not had a label. It is, however, of 
little consequence, the specimen being chiefly quartz, with some intermingled oxide of iron, and 
on one side a stain of carbonate of copper. It somewhat resembles the specimens from New 
Placer, (No. 93.) 
COAL AND FOSSIL VEGETATION. 
No. 98. Bituminous coal, Ojo del Pescado Zuñi.—Very considerable interest attaches to this 
specimen, from the fact of its being the only organized representative, with a label, of the forma- 
tion called Jurassic by Mr. Marcou. He has labelled it as Jurassic—upon what grounds I do 
not know ; for the specimen does not appear to me to present any very decisive evidence of its 
geological age. It much resembles the Tertiary brown-coals or lignites found on the western 
coast. The evidence upon which Mr. Marcou bases his opinion of the Jurassic age of this 
coal, was probably presented by its stratigraphical position. He states, on one of the labels, that 
t occurs between two thick beds of rose-colored sandstone. 
