LINDGREN AND 
HILLEBRAND, 
] MINERALS FROM CLIFTON-MORKNCI, ARIZONA. 45 
bodies of organic chemistry. This is especially true because in so 
many cases the mineral manganites described are far from being 
homogeneous species. They are either mixtures of two or more of 
these closely related complex molecules or else are contaminated by 
foreign bodies. It is not surprising, then, that so many compounds of 
uncertain formula that may be regarded as salts of manganous acid 
have been prepared in the laboratory or are found in nature. From 
the known tendency of these bodies to form under laboratory condi- 
tions which may very well be repeated in their general character in 
nature, it is to be expected that a vast number of mineral manganites 
should exist, and it ought rather to excite surprise than otherwise if 
two or more are not formed simultaneously from the same solution. 
This, together with inherent difficulties of analysis, would offer a 
simple explanation of the fact that so few of the anal} T ses made lead to 
rational formulas. If formed from solution, their original state might 
well be one of hydration either as regards water of crystallization or 
of constitution. The temperature at which the water is expelled in 
the present case indicates constitutional water. 
Our search of the literature has not revealed a native manganite 
earning a high percentage of lead, although artificial compounds have 
been prepared. For this reason, and because of its distinctly ciwstal- 
ine character, the present mineral seems worth} 7 of a specific name. 
The one we propose is coronadite, after the famous explorer of that 
portion of the American continent from which the Territories of New 
Mexico and Arizona have been formed. 
CIIAI.COCITE. 
The cuprous sulphide (Cu 2 S) is very common in the Clifton district; 
n fact, it constitutes at present the principal valuable mineral in the 
pres. It occurs chiefly intergrown with pyrite, in the altered por- 
hyiy, as disseminated grains or as solid seams or veins which rarely 
xceed 2 or 3 feet in thickness. It is never crystallized but has ordi- 
arily an earthy or sooty appearance and black color; scratching with 
ji knife reveals its semisectile character and metallic luster. In a few 
Small massive veinlets the normal metallic luster and dark-gray color 
iippear on fractures; a fibrous or columnar structure of the mineral is 
known on small seams in shale from the Montezuma mine. The 
pineral prefers porphyry, and the great bodies of ore now worked 
11 occur in this rock; but it is not entirely unknown from the irregu- 
ir deposits in limestone generally carrying cuprite and copper carbon- 
tes. A partial analysis of massive chalcocite from the Montezuma 
line, Morenci, gave 96 per cent Cu 2 S and 2.4 per cent FeS 2 , the latter 
robably mechanically admixed. 
The chalcocite is everywhere, in this district, a secondary mineral 
