No. 378.) REVIEWS OF RECENT LITERATURE. 467 
aggregate referred to above. In addition to the two minerals men- 
tioned, it contains also phlogopite, amphibole, and diopside. The 
phlogopite is in phenocrysts. The sanidine and the leucite are usually 
grouped in separate patches, the former in aggregates of stout, square 
prisms, associated with ophitic amphibole and with diopside, and the 
leucite in aggregates of minute anhedra, some of which are enclosed 
in amphibole prisms. The sanidine is filled with inclusions of 
diopside needles. The rock is called orendite. The amphibole of the 
orendite possesses very peculiar properties. While having a prismatic 
cleavage angle of 124°, its extinction appears always to be parallel to 
the c axis. Its pleochroism is a=a, pale yellow; b=4, red; c=<¢, 
bright yellow, and its axial figure is almost that of a uniaxial mineral. 
The rock of Pilot Butte, a mesa separated from the Leucite Hills 
by a valley, is composed of colorless diopside, phlogopite, and, proba- 
bly, perofskite, in a brown glassy base of the composition of leucite. 
This rock, which is probably a portion of a volcanic flow, is called 
madupite. The phlogopite of the madupite differs from that of the 
orendite in that it occurs as roundish grains filled with diopside 
microlites and perofskite grains. The cleavage is not as well marked 
as is usually the case in micas, but the optical properties are those 
of phlogopite. 
The chemical composition of the three types of rocks is represented 
by the analyses following: 
Wyomingite Orendite Madupite 
SiO, = 53.70 54.08 42.65 
TiO, = 1.92 2.08 1.64 
Al,O; = 11.16 9.49 9-14 
Fe,0; = 3.10 3:19 5-13 
eO = 1.21 1.03 1.07 
CaO = 3.46 3-55 12.36 
BaO = .62 -67 8 
MgO = 6.44 6.74 10.89 
K,O = 11.16 11.76 7-99 
NaO = 1.67 1.39 go 
H20 at 110° = 80 79 2.04 
H,O above 110° = 2.61 27% 2.18 
P20; = £95 1.35 1.52 
Other constit. = 80 1.14 1.71 
Totals 100.40 99-97 100.11 
The constituents included among the “other constituents ” are 
ZrO, Ce,0;, Di:O;, Cr-O, MnO, SrO, Li.O, SO;, Cl, Fl, and CO. 
The totals corrected for Fl are 100.21, 99.76, and 99.91. 
