512 T. L. Watson — Kragerite, a Rutile hearing Rock 



usually shows cleavage and twinning, is marked by irregular 

 fractures, and shows some alteration peripherally and along 

 fractures to leucoxene. Inclosures of the silicate minerals, 

 chiefly hiotite, are noted in the rutile, and rutile granules are 

 distributed through the silicate minerals — a relationship which 

 suggests contemporaneous crystallization of the rutile and 

 silicate minerals. Biotite, quantitatively the next mineral to 

 rutile, of brown color, strongly pleochroic, and partly altered 

 to chlorite, is developed in aggregates of shreds which 

 occasionally observe a radial arrangement or grouping. 



An analysis made of the rutile separated from the rock and 

 freed as nearly as possible from silicate minerals yielded the 

 following results : 



Chemical analysis of rutile from Krageroe, Norway, 

 (Wm. M. Thornton, Jr., analyst.) 



TiO, 97-68 



SiO, 1-06 



Fed 0-81 



O 2 0,.. 0-39 



V 2 3 0-55 



Total 100-49 



Specific gravity.. 4-225 (J. Wilbur Watson) 



Chemical Composition and Classification in the New System. 

 The chemical analysis of this rock is as follows : 



Chemical analysis of kragerite from Krageroe, Norway. 

 (J. Wilbur Watson, analyst.) 



Per cent. Mol. 



SiO, 50-52 -842 



Al 2 () 3 13-98 -137 



Fe 2 O s 0-49 -003 



FeO 0-16 -002 



Mj^O 034 -009 



CaO 1-05 -020 



Na 2 0.. 6-18 -100 



K 2 6 .... .... l'OO -oil 



H 2 0- 0-20 



H 2 0+ 0-30 



Ti0 2 25-00 -313 



V 2 0, n.d. 



MnO None 



P 2 5 Trace 



C0 2 None 



S 0-12 -003 



Total 99-34 



