216 Tenth Supplement to Dana's Mineralogy. 



equivalents of water. This water is expelled at a lower heat than in the case of 

 and insoluble alumina, consisted of a mixture of sulphate of potash with subsulphate 

 of alumina. It is partially soluble in chlorhydric acid, while aluuite is perfectly 

 insoluble. Analyses ; 



K JTa XI Fe S U % Ba . Ca Si XW »« 



near*S*teSng. made by Oellacher is given in Kenngott's^Uebersicht for 186M- 

 manQ, Smith and Brush. Composition : 



§i 51 Pe Ca Ba Sr JfT? te ^n ^ ]S;a^ Cu^ t^^^ 



mfwiS iS'if^rinS'^'Pi''^'^^^"* '^' lontaL™\^y ta^^^^^ "^^ ^^f.'f 

 the mineral gave, after long standing, a flight turbidity with sulphate of lime. The 

 spectroscope showed the presence of stronlia and lime, but not any trace of baryta. 



MAROARODrrE [p. 223, Villi.- A variety of mica from Derby, Vt. has been 

 named adamsite by Prof 0. U. Shepard, on account of some supposed peculiar 

 phyMcal properties {Hitchcock's Oeology of Vermont, vol. i. p. 484). It i* f"""'^.'" 

 thickly disseminated cry><taU in mica slate, and Shepard remarks that " its crystamne 

 form is that of mica and but for its perfect inelasticity and greater hardness, it m|M 

 iperiea:' as every one knows that there are se?errU^pecies'''of'^mica.' The specimens 

 of mineral from Ddrby. Ver.nont, received from Prof Shepard, and examined by tM 



Si_ XlFe Ca Mg° Alkalies. ' Ign. 



This corresponds very closely with the analyses of margarodite from ^"""""^'gi^jj 

 properties with margarodite from different localities, leave no doubt as to tbe ^ 

 priety of classing the so called adamsite with this kind of mica.--o. x b.] ^.^^ 



with" tinge of yellowishgreeri : lustre pearly, sub^translucent. Hardness over 

 G.=2-802. Difficultly fusible. Composition : 



Si *1 Pe Ca % K lifa fi ^, ,, 



46-42 37-92 0-46 067 O'lT 963 1-54 4-40 = lOl^l 

 Martite [p. 102, VII].-Dewalque has described an octahedral sesquioxy^^J 

 iron from Frassem near Arlon in Luxemburg. Occurs in regular octahedron^ ^ 

 sandstone. Color black; lustre generally dull; fracture earthy, showing "^ ''' g^ 

 age; streak brick red; sp. gr.,4-35; hardness lb. Composition P*^-. ""'^'y'^ pro- 

 duct of the decomposition of pyntes.— {Kopp, Jahresbericht, 1860, 775.) 



Mica.— For analyses of Black Mica from Canton (Ireland) granite by S. HaugWo"' 

 see Quar. Jour. GeoL Soc DabUn, viii, 160. 



