1887] Mineralogy and Petrography. 71 
which he believes are members of the spinel group. A mineral 
very like those above mentioned also occurs in the tonalite from 
Adamelio. The same author, in another paper, describes a 
peridotite * from Goose Bay, in the Straits of Magellan. It con- 
sists essentially of olivine and enstatite, with picotite and apatite 
magnetite as secondary constituents. The olivine contains gas, 
liquid and glass inclusions. The fibres of the bastite seem to 
ave been curved by some mechanical agency (pressure). An 
analysis of a comparatively fresh specimen yielded, — 
SiO,  Al,O,  Fe,0, CrO, Fe(Mn)O MgO CaO H,O 
43-39 2.26 0.35 10.47 39:89 2.33 1.54 
——Basalts, E a hornblende-pyroxene-andesites, 
hornblende-mica-andesites, and dacites, very like similar rocks 
occurring in the western portion of our own country, are de- 
scribed by Messrs. Hague and Iddings* from the Republic of 
Salvador, Central Ameri Certain “Pliocene sandstones” 
sist of pumiceous dust cemented by calcite or clayey material. 
An analysis of one of these from Little Sage Creek, Montana, 
yielded Mr. Whitfield, — 
SiO, et Paes CaO MgO NaO KEO T loss by ignition 
65.56 258 o: 2.08 ` 6.50 
Mineralo oa News.—The lithia micas of Matic and the i iron- 
thorough chemical examination by Mr. F. W. Clarke and 
the gentlemen associated with him in the chemical department 
of the U. S. Geological Survey. The various types of these min- 
erals, from different localities in the States named, have been 
analyzed, and the results of these analyses are given in a paper 
in the American Fournal of Science By supposing fluorine to 
replace the hydroxyl (HO) group in ortho-silicic acid, a seri 
of fluo-silicic acids may be obtained as a nucleus upon which to 
build the formule representing the composition of the various 
lithia micas. For example, if we represent muscovite by 
F4 SO R. 
Al x SiO,= Al, then lepidolite might be represented by 
S0,=- Al ; 
Al aoe ee 
N SIFO, Wa Al, and cryophyllite by Al = Spee R 
Al ‘a SiO, —R 
S SiFO, = Rz 
t Note sur un-nouveau minéral accessoire de la roche de Beucha (près de Leipzig). 
Bull. de la Soc. Franç i Ae Minbralogie, eix; No. r; —— es. Jahrb. sapi ore ra » ete, 
1986, ii. p. 180. Ib., Sept. 1886, p. 199. 
Amer. Jour. oe, xxxii; Taly, 1886, p. 26. 4 a arni 1886, Pp- 353- 
