SSjumrand? I MINERALS FROM CLIFTON-MORENCI, ARIZONA. 4\) 
A rough preliminary analysis of selected pitch black material from 
me Detroit mine gave 
CuO 28. 6 
Zn( ) 8. 4 
Mn0 2 21.2 
Fe 2 ( ) 3 -fAl 2 :i +P 2 () s 4. 
Insoluble in HC1 22. 8 
Ignition loss 16.3, less oxygen due to conversion of MnOjj to Mn 3 4 . 13. 7 
98.7 
Similar material surmounted by crusts of chrysocolla from the 
Modoc open cut contained much Mn0 2 , with a good deal of CuO and 
Zn( ), and is. thus evidently, the same substance. Manganese is largely 
but not certainly wholly present as Mn0 2 . The insoluble portion 
consists of silica, is wholly separated by acid without need of evapo- 
ration, and is nearly all soluble in dilute potassium hydroxide. It is 
not possible to say whether silica is in combination or as opal, but it 
can not be present in any other form. 
Most of these copper-pitch ores, known from many districts, have 
been described as impure chrysocolla. As shown by the optical char- 
acteristics, they are not, however, a mixture, and they certainly do 
not contain any chrysocolla, the characteristics of which are very 
different. They probably represent a series of closely related com- 
pounds, the chemistry of which has not yet been fully elucidated. 
Prof. G. A. Koenig" describes a similar mineral with the same iso- 
tropic character from Bisbee, and names it melanochalcite. Its com- 
osition is different, since it contains 
CuO 76. 88 
Si0 2 7. 80 
C0 2 7. 17 
H 2 7. 71 
ZnO 41 
FeS 2 07 
100. 04 
Professor Koenig considers it most probably a basic salt of an ortho- 
lilico-carbonic acid. No carbon dioxide was found in the Morenci 
ninorals. In conclusion it would seem that the chemistry of these 
!;opper-pitch ores would bear further examination. 
MORENCriF, 
In a lime shale on the intermediate level of the Arizona Central 
line, Morenci, 200 feet below the surface, brownish or greenish 
breading mases were found, containing brownish yellow, silky fibrous 
nuns. The inclosing material consists largel} 7 of the same material 
a Am. Jour. Sci., ser. 4, vol. 14, Dec, 1902, p. 404. 
Bull. 262—05 4 
