472 RECORD OF SCIENCE FOR 1887 AND 1888. 



This iniueral is of iuterest because it shows that the same form belongs 

 alike to the tantalate aud niobate of iron and manganese, although the 

 mineral ordinarily called tantalate does not conform to this very closely. 

 (Described by A. Arzruni in Verh. Russ. Min. Ges., St. Petersburg, 

 vol. XXIII, 181.) 



Martinite. — A pseudomorphous mineral having the form of gypsum, 

 but consisting chiefly of calcium phosphate ; it is from the guano of the 

 Island of (^ura^oa. It appears in aggregates of minute rhombohedrons, 

 white or yellowish in color. The specific gravity is 2.894. An analysis 

 gave : 



P2O5 CaO H2O Organic Insol. 



47.67 46.78 4.5-2 0.7.5 0.20 = 99.92. 



For this the formula is 20a,(PO4)2, 4 CaHP04+n,0. (Described by 

 J. M. Kloos in Samml, Mus. Leiden, ser. 2, vol. i; abstract iu Jahrb. 

 Min., 1888, vol. i, 41 ref.) 



Mazapilite. — Stated on the basis of a preliminary examination to be 

 an arsenite of calcium and iron. It occurs in deep red to black crystals, 

 having a hardness of 7, and a specific gravity of 3.567. It is from the 

 mining district of Mazapil, Zacatecas, Mexico. (G. A. Koenig in Pro- 

 ceed. Acad. Nat. Sci., Philadelphia, July 3, 1888.) 



Melanocerite. — See Barkevikite. 



MetaloncMdite. — A varity of marcasite from the St. Bernhard mine, 

 near Hausach, Baden. It is peculiar iu containing 2.7 per cent, of 

 arsenic, with some nickel and lead, and hence approaches Breithaupt's 

 lonchidite. (Described by F. Sandberger in Oesterreich. Zeitschr. Berg. 

 Hiitt., 1887, vol. xxxv.) 



Metastihmte. — A form of antimony sulphide, like stibnite in composi- 

 tion, but of a bright red color, like the corresponding compound obtained 

 in the laboratory. It occurs sparingly as an amorphous red deposit at 

 Steamboat Springs, California. (Described by G. F. Becker in Mono- 

 graph xiii, U. S. Geological Survey.) 



Nor den slioldin e. — See B ark e vi k i te. 



Paposite. — A hydrous iron sulphate from the Union mine near Pa- 

 posa, Atacama. It occurs in dark red crystalline masses, having a 

 fibrous radiated structure. The formula obtained by Darapsky is 

 2Fe203, 3S03-f IOH2O, so that it approaches closely to fibroferrite, 

 (Bol. Soc. Min. Santiago, No. 92, October, 1887, iu Jahrb. Min., 1889, 

 vol. I, 23 ref.) 



Pseudohiotite. — An alteration product of the biotite from the crystal- 

 lized limestone of the Kaiserstuhl. The mean of two analyses gave: 



SiOi TiOs AI2O3 FejOj MD2O3 MgO K.^O H:iO 



35.91 1.115 15.18 10.85 0.89 22.80 2.90 10. 77 = ICO. 45. 



It is not to be regarded as a definite compound. (Described by A. 

 Knop iu Zeitschr. f. Kryst., 1887, vol. xii, (307.) 

 RhodotiUte. — A mineral occurring with heliophyllite (see above) at the 



