90 . PHYSIOGRAPHY. 



Bronzite Brookite Brucite. 



are associated with serpentine ; and is immediately connected with mass- 

 ive and crystallized Hornblende, Augite, and Plumbago. Its color is a 

 fine reddish brown, attended with a metallic lustre. It has been ana- 

 lyzed by Mr. T. G. CLEMSOIST, who, under the impression of its be- 

 ing a new species, has bestowed upon it the name of Seybertite, after 

 the American analyst, Mr. SEYBERT. But its identity in form, hardness 

 and sp. gr. with Bronzite, does not appear to justify the attempted dis- 

 tinction. Mr. CLEMSOIT found it to consist of 



Alumina .... 37-60 



Magnesia .... 24-30 



Lime .... 10-70 



Silica .... 17-00 



Protoxide of iron .... 5-00 



Water .... 3-60 



BROOKITE. Diatomous Er ut hron e-Or e. 



Primary form. Right rhombic prism. M on M' 100. 



Secondary form. Low hexagonal prism. 



Cleavage parallel with the shorter diagonal. 



Lustre metallic adamantine. Color hair-brown, passing 

 into a deep orange-yellow, and some reddish tints. Streak 

 yellowish white. Translucent . . . opake, the brighter col- 

 ors are observed by transmitted light. 



Brittle. Hardness = 5-5 ... 6*0. 



1. It contains oxide of titanium, with traces of iron and manganese ; 

 but has not yet been analyzed. The first varieties were noticed among 

 the minerals accompanying Anatase from Dauphiny ; but much finer 

 crystals, some of them half an inch in diameter, have lately been found 

 at Snowdon, in Wales. In both places they are accompanied by Quartz ; 

 and in Dauphiny, besides Anatase, it is attended by Crichtonite and Albite. 



BROWN IRON ORE. (See JLimonite.) 

 BRUCITE. Hem i -prismatic Tourmaline. 



Primary form. Oblique rhombic prism. M on M' 

 112? from cleavage. 



