100 W. MW. Foote—Leadhillite Pseudomorphs in Missouri. 
intendent, Mr. John Kingston, of whom they were obtained by 
Dr. A. E. Foote of Philadelphia. In examining them together 
with crystallized leadhillite, the writer observed one isolated 
scalenohedron possessing the high specific gravity, the perfect 
cleavage and pale green color of leadhillite, which subsequent 
qualitative tests proved it to be. This led to an examination 
of all the material then available and a further search on the 
old mine dump, which yielded several other specimens. 
After Calcite.—The scalenohedrons were found in a chert- 
calamine rock and were generally pure cerussite. In anumber 
of instances, however, leadhillite completely replaces the calcite 
either in hollow forms with the six-sided crystals (twins exhibit- 
ing hexagonal symmetry) in the interior, or by the solid massive 
mineral. In some cases minute crystals of calamine and cerus- 
site are intimately associated on the inner surface of the pseu- 
domorphs, apparently being a secondary crystallization. In 
the absence of crystal planes, the perfect cleavage distinguishes 
the leadhillite from the cerussite, which has a conchoidal 
fracture. | 
The chemical tests consisted simply in dissolving the 
powdered mineral in boiling dilute nitric acid. Cerussite dis- 
solves with effervescence, leaving no residue, while the sulphato- 
carbonate (leadhillite) similarly dissolves but leaves a white 
precipitate of lead sulphate, which settles as the effervescence 
of carbon dioxide ceases. This precipitate gave reactions for 
sulphur on charcoal. 
After Galena.—Pure white leadhillite replaces cubes of 
galena occurring in the same matrix with the calcite psendo- 
morphs, and showing in the same manner the fine crystalliza- 
tion of the leadhillite. 
- In the majority of crystals observed, however, a gray amorph- 
ous mineral in crusts and hollowed forms replaces the cube. 
Again there are many imprints of the galena, empty or par- 
tially filled with leadhillite or cerussite. The gray crusts when 
compact exhibit a slightly fibrous structure with inner surface 
botryoidal; hardness 2 to 25. They gave the same reaction 
as the crystallized mineral except that the residue left was 
gray. After effervescence ceased, this was boiled strongly and 
the residue became white and supernatant liquid clear. 
This incomplete analysis would indicate that the gray color 
is due to the presence of unaltered lead sulphide, which dis- 
solves after the solution of the sulphato-carbonate is completed. 
Several crystals showed patches of bright cleavable galena 
through the altered mass. 
These facts have been thought worthy of note inasmuch as 
no clefinite report of such pseudomorphs has yet been made. 
