MINERALOGY. 281 



lead. It occurs in regular octahedrons ; it resembles urani- 

 nite, having an iron-black color and being quite opaque. The 

 hardness is 5.5, and the specific gravity as high as 7.49. It is 

 infusible in the blowpipe flame, though giving a giobule of 

 lead with soda or charcoal. From the feldspar quarry at 

 Garta, near Arendal, Norway ; described by A. E. Nordens- 

 kiold. 



Cotterite. A variety of quartz, having a peculiar metallic- 

 pearly lustre. It occurs as a coating on ordinary quartz 

 crystals at Rockforest, Ireland ; described by Harkness. 



Dickinsonite. A hydrous phosphate of manganese, iron, 

 calcium, and sodium. It is found in crystalline masses, hav- 

 ing a foliated, micaceous structure. The color is grass-green, 

 and the appearance of the mineral hence very like some vari- 

 eties of chlorite, although it is unlike it in its very brittle char- 

 acter. The crystals have a rhombohedral habit, but in fact 

 belong to the monoclinic system. Found at the locality re- 

 ferred to above, at Branch ville, Conn., with eosphorite, trip- 

 loidite, and other related species ; described by G. J. Brush 

 and E. S. Dana. 



Dietrichite. A hydrous sulphate of zinc and aluminium, 

 referred to the alum group. It has a white to brownish- 

 yellow color, and a silky lustre ; it occurs in aggregated mass- 

 es, having a fibrous structure. It is easily soluble in water, 

 and has the taste of the alums. Found at Felsobanya, Hun- 

 o-arv : it is a recent formation of the last fourteen years ; de- 

 scribed by Von Schroeckinger. 



Duporthite. A hydrous silicate of aluminium, iron, and 

 magnesium. The mineral is greenish to brownish gray, and 

 has a silky lustre. It is found in fibrous masses occupying 

 fissures in serpentine ; it resembles the chrysotile, or fibrous 

 serpentine. Locality, Duporth, near St. Austell, Cornwall ; 

 described by J. H. Collins. 



Ekdemite. A mineral containing lead-arsenate and lead- 

 chloride. It has a bright yellow to green color, a vitreous to 

 greasy lustre, and is translucent in thin splinters. It occurs 

 generally in small coarsely foliated masses imbedded in cal- 

 cite, and also as a crystalline coating. It is referred to the 

 tetragonal system. Found at Langban, Sweden ; described 

 by A. E. Nordenskiold. 



Eosphorite. A hydrous phosphate of aluminium and man- 



