772 The American Naturalist. [September, 
ably present as SiS,, combined in some way with SiO, in the propor- 
tion SiS, + 40 SiO,. G. Friedel,” on the other hand, insists upon 
regarding the sulphur as occurring in the form of sulphate. The 
sigterite from Sigterö, Norway, described by Rammelsberg™ a short 
time ago as a new mineral, is acknowledged by this savant and by 
Tenne to be a mixture of eleolite and albite——-A greenish-white 
fibrous tale from Madagascar” has the composition SiO, = 62.3; FeO 
= 20. Mp0 == 294; BLO = bil: On a specimen of dioptase” in 
calcite from Central Africa Jannetaz has recognized octahedra of 
silver. This is the first report of the existence of native silver in that 
quarter of the globe. Crystals of barite from Smithton and Sedalia, 
Pittis Co., Mo., consist of colorless portions enclosing yellow or white 
bands, in the latter of which Luedeking” and Wheeler find a large 
quantity of strontium and a small amount of ammonium sulphate. 
The composition of the crystals is Ba SO, = 87.2; Sr,SO, = 10.9; 
Da BO, — 2> NH So = 2; BO = 24. In consideration of the 
importance given by Tschermak to meionite in his discussion of the 
scapolite group Kenngott recaleulates the formula of the mineral from 
new analyses recently published and derives Ca, Al,, O,, Si,, O,,. He 
evidently places but little confidence in the Tschermak theory. By 
mingling solutions of chromates, tungstates, molybdates, sulphates and 
selenates and studying the mixed crystals resulting Retgers”* has shown 
that their alkaline and other salts are isomorphous, and that conse- 
quently when they are found as minerals they should all be placed in 
one group, which is trimorphous. The tellurates, on the other hand, 
are not isomorphous with any of the above mentioned compounds.—— 
The walls of cavities of the leucite basalt from the south side of Lake 
Laach are covered with brilliant little crystals that have been carefully 
examined by Busz.” They are hematites on which are implanted rutile 
erystals and little colorless olivines with a tabular habit parallel to 
o Px. All are supposed to be products of sublimation ——A. 
Schmidt” records the results of observations on pebbles of zircon, 
almandine and epidote from Adelaide, Australia. The zircon has a 
Bull. Soc. Fr. d. Min., xiv, p. 74. 
“AMERICAN NATURALIST, 1890, p. 1189. 
%Jannetaz, Bull. Soc. Fr. d. Min., xiv, p. 66. 
*8Tb., xiv, p. 67. 
7Amer. Jour. Sci., Dec., 1891, p. 495. 
Neues Jahrb. f. Min., etc., 1892, i, p. 56. 
*Zeits. f. Kryst., 1891, xix, p. 24. 
wib., 1891, xix, p. 56. 
eS AEA 
