182 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
calaverite crystals is a layer of radial pyrite with a minutely botryoidal surface. 
This layer in turn is incrusted by comb quartz containing some calaverite. The 
structure of this ore is shown somewhat diagrammatically in fig. 13. 
The occurrence of hollow, acicular, or prismatic pseudomorphs, which are 
probably in all cases formed by the incrustation of celestite by a shell of drusy 
quartz and the subsequent solution and removal of the strontium sulphate, fre¬ 
quently gives a characteristic structure to the vein fillings. Sometimes these 
pseudomorphs, which are usually opaque and are milk white or yellow, are com¬ 
pletely embedded in the quartz or, less commonly, in fluorite. In most cases, 
however, they project into the vugs, and with their incrusting quartz crystals 
form a particularly rough crystalline lining, as may be well seen in the Howard 
flat vein in the Ophelia tunnel. The original celestite crystals, as shown by the 
pseudomorphs and by the crystals seen in the C. K. & X. vein, are slender needles, 
usually of rhombic cross section and tapering to a point. In the Howard flat vein 
such needles have been radially incrusted with quartz crystals so as to form little 
stalactites with diameters ten to twenty times that of the original celestite needle, 
and with lengths of 1 or 2 inches. On these stalactites were implanted a second 
generation of celestite crystals which have in turn been incrusted with quartz and 
dissolved away. Some of the pseudomorphs which showed a hollow central canal 
partly filled with a white earthy substance were analyzed by Mr. George Steiger, 
who found that they contained 2.04 per cent BaO, 0.04 per cent SrO, 0.06 per cent 
CaO, and an amount of S0 3 which probably would suffice to form sulphates in 
combination with the bases. It is possible that the original mineral was barite, 
but the crystal form rather points to celestite with a small percentage of baryta. 
During the pseudoinorphic action the more soluble sulphates of strontia woidd be 
carried away, leaving a residual of not easily soluble barite. Some of the hollow 
pseudomorphs found in the ores have cross sections that are sharply rectangular 
instead of rhombic. Such pseudomorphs were observed in the Golden Cycle mine 
and, embedded in chalcedony, in the Blue Bird mine. The original mineral after 
which these shells are pseudomorphs has not been ascertained. It may have been 
celestite of a different crystal habit from that characterizing the known occurrences 
of this mineral in the district. 
EXCEPTIONAL VARIETIES OF VEINS. 
LEAD-ZINC VEINS. 
Narrow veins with quartz gangue, predominating galena or zinc blende, and 
subordinate telluride occur along the western side of the district from Poverty 
Gulch down to Squaw Gulch and the vicinity of the Pointer and Puzzle mines. 
The strike is usually northeasterly. No strict line separates these veins from the 
normal telluride veins. Where there is much galena some silver is present, but 
the high silver values are, as a rule, connected with the occurrence of tetrahedrite. 
Many of the galena veins are close to normal telluride veins. 
