370 Reéxamination of American Minerals. 
From these we obtain the mean oxygen ratio for silica and pro- 
toxyds, and water, 19°84: 14:50: Ll 92=4:3:24, and the form- 
ula R Sit + 7H. 
Atoms. At. wt. Pr. tt 
‘ 2809. =. 8888 
Magnesia, . r 6 ; 4 1500 25:23 
Protoxyd of iron, . 3 3 : 1350 22°70 
Water, : i 7 ; . 188 13°24 
5947 
The mineral is similar in composition to serpentine with one 
atom more of water, and the magnesia replaced in part by pro- 
toxyd of iron and manganese. It also has a strong resemblance. 
to hydrophite, both in chemical and physical properties. 
32. Lazulite. 
This species occurs in considerable abundance in Sinclair Co., 
N. C., which is its only American locality. It is of interest to 
compare its composition with the European varieties, and for that 
reason the examination was made. 
The sp. gravity was 3:122. ‘Two analyses gave 
Oxygen. Ox. 
Jon ag acid, . 43°38==24°31 “4 15 = 24°74 
. 3122 14°59 217 15°03 
Protoxyd of iron, . S29 1-84) 5. * a> 1s t 80 
1006 4-02 t ane voor «6401 55° 
_ Water, : 2 568 5°05 550 489 
Bi, ¢ : 107 ‘ 107 
99-70 “100-96 
No. 1, has the oxygen ratio =24:90 : 14-94 : 6 : 5°16, or very 
nearly 25 : 15:6: 5. 
No. 2, has = 25-56 : 15-54: 6: 5-04. 
Fri. these we deduce the formula 
2(Mg, Fe)* B+ Ay Bs + of 
Atoms. At. wt, Pr. ct. 
Kee acid, i 5 ; 4460 ; 44:02 
5 3209 : 31°67 
Protota of iron, 2 : 00 ‘ 8°88 
Meee : 4 ‘ 1000 i 9°87 
Wat : 5 563 5°56 
The foots differs ae that of Bervinclbeee “i one atom less 
of alumina and of water; calculated by his formula it would give 
the alumina much too high for our analyses. e phosphoric 
acid was separated from the alumina, by fusing the mineral with 
carbonate of soda and silica, this being the most perfect method, 
in fact the only one to be safely relied on. It appears to be iden- 
tical in specific gravity and composition with the variety from 
Gratz examined by Rammelsberg. 
