244 Eakle and Muthman—So-called Schneebergite. 
Art. XXIV.—On the so-called Schneebergite; by A. 8. 
EAKLE and W. MUTHMAN. 
In the year 1880, A. Brezina* published a short announce- 
ment, “Ueber ein neues mineral, den Schneebergit,” which 
was found on the Bockleitner Halde at Schneeberg in Tyrol. 
A qualitative analysis by H. Weidel gave as the principal con- 
stituents antimony and calcium, so Brezina supposed it might 
be a second modification of romeite or romeine, which accord- 
ing to Damour should have the formula Sb,O, . Sb,O,. 3CaO. 
Groth in his “ Tabellarische Uebersicht der Mineralien ” gives 
as the most probable formula for romeite CaSb,O, and for 
schneebergite Ca,Sb,O,, making this last identical with atopite. 
A quantitative analysis of the schneebergite had not been 
made, so it appeared to us desirable to make one with a small 
amount of clean material. The mineralogical collection here 
contains a series of specimens of this rare mineral from Schnee- 
berg, the greater part of which were collected at different 
times by von Elterlein during his study of the mineral deposits 
of that locality. 
Most of the mineral appears as crystalline aggregates upon 
the ore, which latter consists of a mixture of magnetite, zinc- 
blende and chalcopyrite; the gangue mineral is massive quartz. 
The aggregates are partly kidney-shaped and consist of 
rounded crystal grains, with scarcely recognizable form. The 
color varies from honey-yellow to bright wine-yellow; the 
surface is often brown from a slight decomposition, the color 
being due to a thin coating of iron hydroxide. The perfectly 
fresh, undecomposed crystals are isotropic and occasionally 
show weak and abnormal double refraction, especially when 
they contain inclusions of fine particles of the ore. 
On other ore-specimens the mineral appears as thin coatings 
or aS a deposit; occasionally can well defined crystals be 
observed, all of which show the single form of the octahe- 
dron. The crystals are generally accompanied by calcite aud 
breunerite, from which the mineral has evidently originated, as 
has been shown by v. Elterlein ;+ commonly the schneebergite 
surrounds the calcite, if it has not entirely replaced it. The 
paragenesis can be followed still better in sections under the 
microscope. It can be seen that the calcium-iron carbonate 
changes at first to a light yellow, double refracting mineral of 
indefinite composition, which by further change becomes gran- 
ular and isotropic and finally passes into the pure schneebergite. 
* Verhandl. d. k. k. geolog. Reichsanstalt, 1880, 313. 
+ Jahrbuch der k. k. geolog. Reichsanstalt, 1891, xli, 336; Zeitschr. fur Kryst., 
xxiii, 283. 
