250 Identity of Edwardsite with Monazite. 
added that the prism was terminated by a four-sided pyramid. 
He observed that the cleavage was sometimes perfect, but gene- 
rally uneven parallel to the oblique terminal plane, but very per- 
fect parallel to the longer diagonal. He further remarks that it 
bore the closest resemblance to zircon, which the Monazite was 
supposed to be by Menge, who first found it in the Ilmen branch 
of the Uralian chain. The few measurements of Edwardsite 
nearly correspond with those of Monazite, excepting the inclina- 
tion of an oblique terminal plane to the plane replacing the ob- 
tuse lateral edge, which, with Monazite, gave an angle of 100° 3’, 
- with Edwardsite 103° 58’, but the calculation of the former was 
grounded on imperfect measurements. In regard to form, there- 
fore, the two minerals correspond. — 
“They also resemble each other in relation to other properties. 
Color, hyacinth red to reddish brown, the lustre of Edwardsite 
somewhat stronger ; hardness = 5 (apatite). Specific gravity of 
Edwardsite is rated too low by Shepard = 4.2 to 4.6,—that of 
Monazite, according to Breithaupt = 4.992 to 5.079. In behav- 
jor before the blowpipe alone, or with fluxes, both alike, both in- 
fusible. Shepard observes that the former fuses with great difli- 
culty on the edges, but no such fusion was observable on the 
specimen in the royal cabinet. There are some differences in 
their behavior with acids, the former, according to Shepard, being 
slightly affected by aqua regia, the Monazite, according to Ker- 
sten being decomposed by chlorohydric acid with the evolution - 
of chlorine. | 
“The apparent differences of their chemical composition may 
be reconciled. The Monazite was analyzed by Kersten, the 
Edwardsite by Shepard. 
Monazite. 53 
Peroxide of cerium 26.00 | Peroxide of cerium 56. 
Oxide of lanthanium, — 23.40 | Zirconia, a 
orina, 17.95 | Alumina, 4.4 
Peroxide of tin, 2.10 | Silica, 3.23 
Protoxide of manganese, 1.86 | Protoxide of iron, 
eon . 1.68 | Glucina, spree 
Pitan : 3 
Potasa,  §—taces.| acid, > 2606 
o¥ See 4 3 
Phosphoric acid, 28.50 | - 9873 
