12 CONTRIBUTIONS TO MINERALOGY. [bull.262. 
canyon is cut in the characteristic " Red Beds " of the Dolores formation. 
Above the Dolores comes the La Plata sandstone in typical develop- 
ment, as described in the Telluride folio, viz, two heavy beds of light- 
colored sandstone, separated by a much thinner bed of dark limestone. 
The roscoelite occurs as an impregnation in the lower bed of the La 
Plata sandstone, about 100 feet above the base, and just beneath the 
bed of dark limestone. All the beds at this point are practically hori- 
zontal. The dark green vanadiferous sandstone occurs in a nearly 
continuous band, approximately parallel to the bedding planes, and 
varying in thickness from a few inches up to 5 or feet. This banc 
extends along the sandstone cliffs for an estimated distance of aboul 
2,000 feet. The roscoelite more or less thoroughly impregnates por- 
tions of the line-grained sandstone which constitutes the mass of the 
bed. It sometimes makes up more than 20 per cent of the vanadif 
erous facies. Normally the sandstone of this lower bed of the Li 
Plata is light buff in color, with patches, mottlings, and stripes of pah 
pink, the latter color being apparently due to small amounts of ferri 
oxide. But when richly impregnated with roscoelite this light-coloree 
sandstone becomes dark olive-green, the contrast being most market 
when the cliffs are wet. Although fairly continuous for the distane 
stated, this zone of vanadiferous sandstone is by no means regular 
It varies much in thickness, and in one place splits into two or mor- 
branches. At some points two or more distinct streaks of roscoelite 
bearing sand were found at different horizons in the main sandstone 
bed. The carnotite is not nearly so abundant as the roscoelite at thi 
locality. It occurs as minute yellow specks in the sandstone, and pai 
ticularly as thin horizontal seams or streaks near the. bottom of th 
vanadiferous zone. 
The work thus far done on the several claims which have bee 
located along these deposits is of the most superficial character. O 1 
the Canary claim Mr. A. B. Frenzel has run a tunnel, about 18 fe< 
long, which exposes a typical section of the impregnated zone. Tl 
roof of the tunnel is formed by the under side of the bed of dark linj 
stone previously referred to. This limestone is underlain by a fe 
inches of sandy limestone which passes into the light-buff La Pla 
sandstone without break. The latter contains abundant calcite as 
cement or matrix for the sand grains. At a distance of a foot belo 
the limestone, the sandstone shows, on close inspection, numeroi 
specks of carnotite and gives a qualitative reaction for vanadiu 
(Hillebrand). Examined in thin section under the microscope, th 
portion of the bed shows a line-grained homogeneous sandstone, 
which well-rounded grains of quartz are held together by a rath 
abundant matrix of calcite. The calcite is crystallized as a fine gran 
lar aggregate and includes small indeterminable particles of vario 
kinds. Many of the quartz grains, as seen in section, are entire 
surroundeel by calcite, and so isolated from adjacent grains. A pi 
