1893.] Mineralogy and Petrography. 901 
of a dark tetrahedrite-like mineral associated with stibnite and pyrite. 
The dark mineral is steel-gray, with a black streak. Its hardness is 3 
—4 and density 5.5. Measurements of the crystals, some of which are 
1 em. long, indicated an orthorhombie symmetry. "Twenty-one forms 
were observed, and from these the axial ratio a : b : e = .6771 : 1 : 4458 
was determined. An analysis gave : 
Cu Ag Fe Sb S Total 
149 11.81. 658 45.03. 3589 = -100.50 
which corresponds to the formula (Ag,. Cu,. Fe) (SbS,),, or a salt of 
normal sulph-antimonic acid. Sundtite presents no analogies, either in 
composition or in its crystallographic characteristics, with other sulph- 
antimonates. Its ‘nearest crystallographic relative is deschynite 
(RNb,O,). The new mineral is a commercially valuable ore of silver. 
Melanostibian is another new mineral obtained by Igelström” from 
the celebrated manganese mine, Sjógrufvan, Grythyttan, Orebro, 
Sweden. It occurs as narrow veins in the dolomite, which is the 
bearer of all the ores of the mine. The mineral is in raven black, 
metallic-looking masses and tiny crystals, that are either tetragonal or 
orthorhombic. The streak of the mineral is cherry red, and its hard- 
ness 4. It is insoluble in dilute hydrochloric acid, but slowly dis- 
solves in boiling acid. Its composition, corresponding to 6(Mn Fe)O 
Sb,O,, was deduced from the following figures: 
Sb,O, FeO MnO CaO MgO HO Total 
37.50 27.80 2962 197 1.03 1.06 = 9848 
Graphitite.—Upon treatment with nitric acid under certain condi- 
tions, the graphite from Ceylon, Norway and Canada yields an oxida- 
tion product that is different from the corresponding product obtained 
from the graphite of Fichtelgebirge, Siberia and Greenland. The 
materials of the two groups are therefore regarded by Luzi” as differ- 
ent, and as worthy of distinctive names. The mineral from the last- 
named localities is called graphitite. 
American Minerals.—The cookeite of Paris and Hebron, Me., 
has been known for some time as a micaceous mineral closely related 
to the chlorites. In habit its plates are hexagonal, and are nearly 
always arranged in radial groups. These plates, according to Pen- 
15 Tb. p. 246. ; 
16 Ber. d. deutsch. chem. Ges., XXVI, p. 890. 
