1260 General Notes. | [ December, 
line, mica, glass, and perhaps melilite can be found by the 
microscope. 
The leucite is remarkably clear and fresh, and shows in polar- 
ized light the well known twinning structure, even better marked 
than in the leucite of the Vesuvian lavas or of the Laacher-See. 
While generally in rounded masses, the smaller individuals are 
often clearly octagonal in outline. The microscope shows the 
leucite to contain many inclusions, among which are augite, 
apatite, olivine, plagioclase, magnetite, nepheline and glass inclu- 
sions and bubbles. ; 
Leucite has as yet never been found in rocks of pre-Tertiary 
age. 
ENARGITE FROM Montrana.—An arseniferous copper ore from 
Montana has been examined by Mr. Wm. Semmons,’ who has 
found in it crystals of a mineral resembling enargite. The crys- 
tals are rare and small. They show prismatic and pinacoidal 
planes, the macro- and brachydomes and the basal pinacoid, and 
are apparently orthorhombic. They are highly striated, like 
stibnite, and cleave into little rhombic prisms. H = 2.5. Spec. 
grav. = 3.92. Soils the fingers. Color lead-gray when freely 
broken, tarnishing on exposure, and then resembling blen 
Streak black. Before the blowpipe it decrepitates and exfoliates 
into worm-like threads like vermiculite, and gives reactions 
for sulphur, arsenic and copper. 
Composition : mean of two analyses: 
Cu As S SiO, F 
45-78 18.65 31.30 2.50 80 = 99-03 
As the hardness, the cleavage and the blowpipe pans 
differ from typical enargite, although the composition Is t gba 
it is possible that this is a distinct species falling smo pr 
other sulph-arsenites of copper as famatinite, clarite, lagoon 
guayacanite. Itis desirable that crystallographic measur 
should be taken. 
occurring at 
oa iful lazulite 
LAZULITE From GEORGIA.—The beautiful been known; 
Graves mountain, Lincoln county, Georgia, has long Dee! in 
but has until now not been investigated optically. aisi Von 
sky-blue crystals often over an inch in length and in wi Fine | 
Lasaulx? of Bonn has recently examined it optical ly. directio 
ochroism was noticed, the crystal being colorless 1n ne axes lie 
of elasticity, and sky-blue in the two others. T ne wga 
in the plane of symmetry, their divergence in air rtain kn 
The angle between the bissectrix (negative) and aa 
planes is also given. The microscope showed that 
1 Mineralogical Magazine, 1884, VI, No. 27, p- 49- 
; 1883, P 274" 
2 Sitzungsber. der niederrhein. Ges. für Natur. und Heilk. December, 
