246 Reexamination of American Minerals. 
abundance, forming, from the manner of i: 
its occurrence, very beautiful specimens. — 
The crystals present a variety of modified See 
forms, tabular and octahedral, one of which 
is here figured. 
Other forms are 0, 1. 
Uae eed © —— 
_ 0, 3, w-o. (Fig. 1.) 
Specific gravity of a dark yellow variety, 6-95. 
€ composition of both the yellow and red varieties was ex- 
amined ; the difference of color is due to the presence of vanadic 
aeid inthe red varieties, and the intensity of color is proportional 
to the amount of vanadic acid, which in no instance is muc 
more than one per cent. 
i 
* 
The analyses afforded 
i z y Yellow variety. Red variety. 
Molybdiec acid, - ee 88°68 37:47 
Vanadie acid, - - - - — 1:28 
Oxyd of lead, - - - - 6048 60:30 
The second corresponds very nearly to 97 p. ct. of molybdate 
and 3 p. ct. of vanadate of lead. As the last substance varies in 
Wulfenite occurs alone on crystallized and cellular quartz, or 
associated with pyromorphite, whose beautiful green color is of- 
ten very much enhanced by the contrast of the yellow and red 
Sometimes the wulfenite forms the mass, and crystals of py- 
romorphite are sparsely disseminated over the surface. It isa | 
found in decomposed granite—on carbonate of lead and oxyd of 
manganese—also associated with vanadate of lead. 
51. Vanadate of Lead ( Descloizite ?) 
This species has never before been remarked among American 
minerals, although the chloro-vanadate (vanadinite) was first dis-_ 
covered in Mexico. ‘This adds another to the list of curious min-— 
erals from the Wheatley mine. It was noticed about a year ago 
in the form of a dark colored crystalline crust, covering the sur- 
face of some specimens of quartz and ferruginous clay associated 
with other minerals. Observed with a magnif ing glass, it is 
Seen to consist principally of minute lenticular erystals, grouped 
together in small botryoidal masses; the crystalline structure 1S 
perfect. Thus seen, the color of the mass is of a dark e, 
