A, A, Julien on Minerals of the Key of Sombrero. 373 
. i. 2CaO, vr 39 HO, 5:50 PO,, 43°61 3aq, 16°50 = 100. 
3 2, 5°42 5°67 41-90 17-01 = 100. 
‘ Its ae to brushite and succession in amount of water 
. have therefore fi designated in the prefix of its name (wera, 
. after). In its characteristics it bears a strong resem- 
blance to pat a mineral which, it may be stated, does not 
) occur upon t fam indebted to Prof. J. D. Dana for the 
following results of his crystallographic examination of meta- 
brushite and its Lap Anica ee 
“System monoclin Oceurring planes the prismatic 7-7 
(orthodiagonal) and 7-2 F clinotiagcnal) with a hemidome which 
may be lettered —1-7, as shown in the eee sectional figure, 
(fig. 2,) ¢é on —1-i=41° 30’—42° 30’, as measured = 
with the common goniometer, but warye in apr = 
cases between 38° and 46°. rge crys- 
tals, which vary from a fourth of an inch to an inch 
in length, often nearly half as broad as long, with 
commonly only 7-7 smooth, —1-7 being crossed verti- 
cally by a few deep furrows and ridges, and round- 
ing either side into 72, which is also uneven from a 
series of furrows parallel to those of —1-7, (see fig. 
3). Cleavage clinodiagonal, easy and pearly. The 
crystals differ in the occurri ing planes from — - 
brushite, although like them in being of the m 
clinic system, and in having a pearly Eincdbiigdial 
cleavage. They approximate moreover in the 
le 2-¢: -1-7; ie calculation gives for this angle 
in brushite (in which the plane -1-i does not occu 
S: 
41° 44’, 
Paci nhs. —Pseudomo ese ent.” (hollow crusts or 
shells) in eed abundance have been found in certain 
localities in the course of quarrying. Of these 
at least the two ‘ilewine varieties may be 
hesitatingly referred to metabrushite, Paid 
the same form and the peculiar marrow es planes. 
ve-—H. =3-25. Sp. gr.=2°971. Color } 
usually very thin, brittle, and fragile. The ex- 
terior surface is tole rably smooth “(on t the ae 
roe plane,) though without lustre ; but th 
Ba and irregular. Both sree are often, but? B 
ints, which 
th the microscope are tiny rhombs of calcite. 
Aw. Jour. Sct.—SEconp SERIES, You XL, No. 1S 1. z 
. 48 
