Mineralogy and Geology. 



125 



20. Muramontite, a new mineral; by M. Kerndt, (Jour. f. Prakt. 

 Chem., xliii, 207.) — Under this name the author designates a ceriferous 

 mineral from near Marienberg in the Erzgebirge. It occurs in black 

 amorphous grains, with a greenish reflection. Density 4*263 to 4*265. 

 It consists of silica 31*09, alumina 2*23, glucina 5*51, yttria 37*14, pro- 

 toxyd of iron 11*23, magnesia 0*42, protoxyd of manganese 0*90, lime 

 0*71, soda 0*65, potassa 0*17, protoxyd of lanthanum 3*53, protoxyd of 

 cerium 5*54, water 0-82=99*94. 



21. Monazitoid, a new mineral from near Lake llmen ; by M. Her- 

 mann, (Jour, fur Prakt. Ch., xl, 21 ; Annuaire de Ch., 1848, p. 146.) 



Monazitoid is a variety of monazite, hardly distinguishable in exter- 

 nal characters, consisting of oxyd of cerium 49*35, oxyd of lanthanum 

 21*30, lime 1*50, phosphoric acid 17*94, substance resembling tantalic 

 acid 6*27, water 1*36, magnesia and protoxyd of iron, a trace. It has 

 thence the formula, according to Hermann, 5(CeO, LnO) PhO, and 

 differs from monazite in containing a tantalic substance in place of tin. 

 Its density is 5*281. 



22. Crystallization of Uralorthite ; by N. von Kokscharov, (Ver- 

 handl. der Russ.-Kais. Min. Gesellsch. zu St. Petersburg, Jahr 1847.) 



The author, in an elaborate memoir, points out close relations be- 

 tween the crystallization of Uralorthite, Allanite and Epidote, and 

 shows them to be isomorphous. The following are two of his figures 

 from Plate iv. 



1. 



la. 



2. 



2 a. 



#***♦-- 



The dimensions (placing a for the vertical axis, b for the clinodiago- 

 nal, and c for the orthodiagonal) are as follows: 



Uralorthite, a: lie ss. H491B: 1 : <H4610 i— 65° 5 



Epidote, 



a:b:c 



1-16050:1: 063653 



34* 



The description of figure 1, according to Naumann's system of 

 notation, is as follows. 



OP 

 M 



QCPX +P30 -HP* +P 



T 



r 



s 



u 



P ocP ocP2 



d z u 



