AKI'VEDSONITE. 303 Pehrsberg in Sweden, Schmalzgrube near Marienberg in Saxony, Bhonsberg in Bohemia, Greenland, and in a brown amphibole, G = 3’26...3'3l, from La Prese near Bormio. Analyses a of the amphibole from Greenland by Arfvedson, b from La Prese by Kudernatsch:— Silica Alumina .... Magnesia .... Lime Protoxide of iron Protoxide of manganese Silica and titanic acid . a b 41'81 45-31 12-14 11-88 11-20 14-28 11-55 10-49 19-60 15-93 1-47 trace — 0-66 168. ARFVEDSONITE.—Arfvedsonite; Phillips. Perito- mer Augit-Spath; Mohs. Arfvedsonit; Hausmann, Haidinger. Probably isomorphous with amphibole. b oio, m no. mini 123° 65' Cleavage, m, very perfect; b, imperfect. Fracture imper fect conchoidal. Opaque. Lustre vitreous. Black. Streak greyish-green... celadon-green. II = CO. o = 3'328...3'4l. In thin fragments melts in the flame of a candle. Before the blow'pipe melts very easily, with ebullition, into a black, mag netic bead. With borax yields a glass coloured by iron. The oxygen in the silica and alumina together is to the oxygen in the bases as 12 to 6. Analysis of arfvedsonite a by v. Kobell, and b of a greyish- black mineral from an island near Brevig, having the form of amphibole, erroneously called aegirine, and supposed to be a variety of arfvedsonite, by Plantamour:— a b Silica 49'27 46"67 Alumina 2"00 341 Protoxide of iron ... . . 36-12 2C38 Soda 8’00 7'79 Potash trace 2-90 Lime i"60 6‘9i Magnesia 0’42 6-88 Protoxide of manganese . . 0 62 2'06 Chlorine . 024 ti 2 - 02
