Mineralogy and Geology. 121 
f 
the relation between the vertical and a lateral axis to be as 689 : 418. 
The inclination of P or the terminal plane, on the four faces in succes+ 
sion, observed between P and M, (a lateral plane of the prism,) are as 
follows :—P : b2==154° 33/, (154° 32’ observed by Breithaupt;) P:b', 
136° 25/ (136° 23, by Breithaupt ;) P : b}==117° 43’; P: b}== 122° 94’. 
Perowskite is a titanate of lime, from the Ural, and occurs in modified 
cubes. Dxscnorseaux figures a very complex crystal with 7 planes on 
each edge, and 10 on each angle, or 164 faces in all. The modifica- 
tions are in part hemihedral. 
42. Baryto-calcite ; MM. Desctoiszaux and Dumas, (Ann. de Chim. 
et de Phys., x11, 1845, p. 425.)—This mineral assumes two distinct 
forms, one an oblique rhombic prism and the other a right rhombic ; 
the former is from Alston Moor, and the latter from Fallowfield. 
Analyses by DesctoisEaux and Dumas confirm the view that they are 
identical in composition ; the formula is 6 Ba--C Ca. 
43. Fluids and Crystals in Topaz, by Sir Davip Brewster.—These 
crystals and fluids, occupying cavities in topaz crystals, have been found 
to be of various kinds. The crystals present the following different 
forms. Cube, cube with truncated edges and angles, rhombohedron, 
prism with plain and pyramidal summits, rhomboidal plates, hexago- 
nal plates, and long rectangular plates ; and Sir Davip has determined 
that there are two distinct substances under a tesseral form, and three 
others among the remaining forms. They are operated upon very dif- 
ferently by heat, some dissolving easily and others not at all. 
The fluids are of two kinds, one dense and the other light and vola- 
tile. By heat they sometimes made their way out of a cavity between 
the lamin to some other resting place or to the surface, the lamine 
closing together after the passage of the fluid. 
44, Phacolite observed in New York, (communicated by Mr. At- 
cer.)—Mr. Atcer has detected this mineral among specimens of min- 
erals received from Messrs. Matruews and Jounson, of New York 
city. It was labelled stilbite, but proves on examination to be phacolite. 
It occurs in geodes, the crystals implanted on cale spar, and associated 
with silvery mica, and a few scales of specular iron. They are of a 
wax or honey-yellow color and a waxy lustre, translucent and brittle. 
It is extremely scarce. 
45. Yttro-cerite, (ib.)—This rare mineral has been found by Mr. At- 
GER associated with Brucite, in masses of rolled limestone from the town 
of Amity, Orange County, N. Y. 
46. Dysluite identical with Automolite, (ib.)—Mr. AucER states that 
from recent observations of the New Jersey specimens, he is satisfied 
there is no reason for any longer considering the two minerals distinct. 
Srcorp Series, Vol. 1, No. 1.—Jan. 1846. ee 
