PHYSIOGRAPHY. 



Huraulite. 



HURAULITE. 



Primary form. -Oblique rhombic prism, M on M=6280 ; . 

 P on M = 101 1^. 



Secondary form. Primary, having its acute lateral edges re- 

 placed, and terminated by dihedral summits. 



Lustre vitreous. Color yellowish-red, to reddish-brown. 

 Hardness = 3-5. Sp. gr. =2-27. 



1. Before the blow-pipe, it fuses very easily into a metallic, black 

 globule, which is taken up by the magnet. 



2. Analysis. 



By DUFRESNOY. 



Phosphoric acid . . . . . . 38-00 



Protoxide of iron ...... 11-10 



Protoxide of manganese . . . . . 32-85 



Water . .... 18-00 



3. It is found in little masses, dispersed through graphic granite, near 

 Limoges in France, and is accompanied by an olive green, fibrous .Viv- 

 ianite. The graphic granite, however, is not found in place. With the 

 Huraulite is found a massive mineral in scales, fibres, and. impalpable, 

 which is supposed to be the same substance. The scaly variety is of an 

 intense, reddish- brown color, and a bright pearly lustre. 



HYACINTH. (See Zircon.) ^ 



HYALITE. (See Opal.) 



HYALOSIDERITE. 



A partially decomposed variety of Peridot. 



HYDRATE OF MAGNESIA. (See Native Magnesia.) 

 HYDRARGILLITE. (See Wavellite.) 



HYDRO-CARBON. 



Primary form unknown. Crystals acicular. 

 Lustre pearly. Color white, or yellowish-white. 

 Sp. gr. = 0.65. 



HYDRO-CARBONATE OF LIME. 



The variety Chalk of Calcareous Spar, altered by having been 

 subjected to the influence of trap dykes. It occurs at the Giant's 

 Causeway in the north of Ireland. According to DA COSTA, it 

 consists of four atoms of carbonate of lime, and three atoms of wa- 

 ter. 



