392 Miscellanies. 



8. Twnen^e, from Dauphinee 5 lustre, adamantine; color, yellow 

 and brown, transparent and translucent. 



9. Busiainite, from Mexico; drusy, of a bladed structure; color 

 gray, greenish and reddish; is almost opake, and scratches felspar; 

 specific gravity 3.1 to 3.3; it consists of 48.90 silica, 36.06 oxide of 

 manganese, 14.57 lime, 0.81 protoxide of iron. It will take its place 

 near the silicate of manganese. 



10. Stilpnomelan, from Silesia. It occurs in fibrous, radiated and 

 compact masses ; colors black and green ; lustre greasy ; is opake ; 

 specific gravity 3. 



11. Brookite, from Dauphinee and Wales, with Anatase. The 

 crystals are rhombic prisms, with the angle of 100°; lustre metallic 

 adamantine; color brown, orange yellow, reddish; translucent to 

 opake; hardness 5.5 to 6.0. 



12. Polymignite, from Norway, in zircon sienite. The crystals 

 are rhombic prisms; conchoidal fracture; metallic lustre; black 

 color; is opake; sp.gr. 4.8; it consists, according to Berzelius, of 

 46.30 titanic acid, 14.14 zirconia, 12.20 oxide of iron, 4.20 lime, 

 2.70 oxide of manganese, 5.00 oxide of cerium, 11.50 yttria. 



13. Pyrochlor, from Norway, in zircon sienite. It occurs in oc- 

 tahedrons ; conchoidal fracture ; smooth surface ; lustre vitreous and 

 greasy; color brown; is opake; sp.gr. 4.2; it consists, according to 

 Wohler, of 62.75 titanic acid, 12.85 lime, 5.18 protoxide of urani- 

 um, 6.80 impure oxide of cerium, 2.75 oxide of manganese, 2.16 

 oxide of iron, 0.61 oxide of tin, 4.20 water. 



14. PyrophylUte, from the Ural. This mineral has been known 

 to mineralogists under the name of radiated talc, (steatite,) but its 

 behavior before the blowpipe is very peculiar. Heated by itself, it 

 swells up in leaves and increases into a volume twenty times greater 

 than its original bulk, and the dispersed mass is infusible ; heated in a 

 retort, water is condensed in the upper part, which does not injure 

 the glass, and does not leave silex by evaporating. Soda dissolves 

 the mineral with effervescence; heated with a solution of cobalt, it 

 becomes of a blue color. It is therefore distinguished from steatite, 

 by its relation to solution of cobalt, the water which it contains, and 

 by its division in separated leaves. According to R. Herman, of 

 Moscow, it consists of 5.62 water, 59.79 silex, 29.46 alumine, 4.00 

 magnesia, 1 .80 oxide of iron, some oxide of silver, and has the for- 

 mula M'g'S'"i'+SA"'l^S'''i' + lOH. 



