DEPARTMENT. OF MINERALOGY 123 
DEPARTMENT OF MINERALOGY. 
HROUGH Edward L. Dufoureq, the President and the Board 
of Directors of the Minas Pedrazzini Company at Arizpe, Son- 
ora, Mexico, have presented to the mineral cabinet a very 
remarkable specimen of crystallized Polybasite. This ore of silver 
(sulphantimonide of silver with some of the silver replaced by copper) 
furnishes a large part of the vein material from which the silver is ob- 
tained in this very productive mine. At favorable points there have 
developed beautifully crystallized specimens of the mineral upon a scale 
of magnitude almost unique. ‘The entire mass as forwarded consisted 
of a crystallized surface, displaying small and large crystals, nestling 
upon an ore body of considerable size. The value in bullion of this 
unusual aggregate was $640 ($1280 Mexican), and it probably was 
the largest mass of Polybasite ever taken from a mine entire. It suffered 
breakage in transit and separated into two specumens which were still 
of great value. Fortunately these were contrasted in character, since 
one contains the great tabular crystals (8 inches across) of Polybasite, 
and the other less unusual smaller crystals, intersecting and merged in 
the more irregular mass beneath. While the breaking of the specimen 
is most regrettable, the splendor of the large crystals becomes perhaps 
more imposing by this removal from their smaller and less significant 
associates. ‘lhe crystals are six-sided plates of the orthorhombic sys- 
tem, slightly protuberant in the center and sharply striated or ruled. 
‘They intersect at nearly right angles, making a cellular box-like struc- 
ture that seems to be characteristic, since a similar disposition is observed 
in the smaller crystals. 
Some interesting minerals from the famous Broken Hill mines of 
New South Wales have been purchased through the Bruce endowment. 
This locality, which has furnished so many superb mineral examples to 
collections, notably specimens of Stolzite (lead tungstate), Cerussite, 
Anglesite, Azurite, with crystallized Cerargyrite, Embolite, and the very 
rare Minersite, has been largely exhausted, but a Mrs. Slee, the widow 
of a mining engineer employed in the mines, brought to this city a group 
of valuable specimens, representing a collection made by her husband. 
‘These mines are situated in the Silverton District and Barrier Ranges 
of New South Wales and have at some points yielded extraordinary 
