404 PHYSIOGRAPHY. CLASS n. 



effervescence in heated muriatic acid. In a high degree 

 of temperature the zinc is driven off, and a hard compound 

 of iron and manganese remains. 



2. The dodecahedral Iron-ore is found imbedded in pris- 

 matic Zinc-ore and rhombohedral Lime-haloide in several 

 mines in Sussex county, New Jersey, in North America. 

 Those crystals which present the most distinct forms, are 

 imbedded in the prismatic Zinc-ore, and not those in the 

 Lime-haloide. But already these exhibit rounded faces on 

 the solid angles of the octahedron, which, being enlarged, 

 are the only ones remaining in the irregular grains imbed- 

 ded in the rhombohedral Lime-haloide. 



4. RHOMBOHEDRAL IRON-ORE. 



Rhomboidal Iron-Ore. JAM. Syst. Vol. III. p. 199. Man. 

 p. 245. Specular Iron. Red Iron-Ore. PHILL. p. 224. 

 228. Eisenglanz. Rotheisenstein. Thoneisenstein (in 

 part). WERN. Hoffm. H. B. III. 2. S. 229. 239. 274. 

 Blutstein. HAUSM. I. S. 256. Eisenoxyd. LEOXH. S. 

 336. Fer oligiste. Fer oxyde' (in part). HAU Y. Traite', 

 T. IV. p. 38. 104. Fer oligiste. Tabl. comp. p. 94. 

 Traite, 2de Ed. T. IV. p. 5. 



Fundamental form. Rhombohedron. R = 85 58'. 



Vol. I. Fig. 7. 



a = V 5-6041. 

 Simple forms. R oo (o) ; R 4- = 1 70 15' ; 



R S (y) = 160 42'; R 2 (*) = 142 56'; 



R 1 = 115 7 ; R (P) ; R + 1 (fc) = 68 



42' ; R + oo (r) ; P + 1 (n) = 128 (X, 122 29'; 



f P + 3 = 121 5', 159 16'; P + oo (z) ; 



(P _ g) 5 (^) 117 58', 139 49', 118 21'. 

 Char, of Comb. Rhombohedral. 

 Combinations. 1. R oo. R. Sim. Fig. 111. and 

 Fig. 119. Vesuvius. 



