Hidden and Pratt — Associated Minerals of Rhodolite. 465 



Bronzite. — This mineral is rare but occurs as highly etched 

 fragments which are pale yellow to deep brown in color and 

 are perfectly transparent, a very exceptional quality of bronz- 

 ite. A beautiful silky sheen sometimes shines out from it 

 when held at the proper angle similar to that seen in the 

 chrysoberyl cat's-eye. The largest piece weighed \\ grams and 

 furnished a beautiful gem, much resembling the brown tourma- 

 lines from Ceylon. With the hand dichroscope it exhibited 

 beautiful brown and green colors. 



The specific gravity of the mineral is 3*43 and its fusibility 

 5i to 6. 



A little bronzite has been found associated with a very dark 

 green massive amphibolite occurring as erratic bowlders. 



lolite. — The iolite has been found abundantly embedded in 

 small bowlders of a granular quartz. The rock has very much 

 the appearance of a conglomerate with quartz as the cement- 

 ing material, and it could be well called an iolite pegmatite. 



The surface iolite has undergone alteration and left the 

 quartz cavernous and cellular, and only by breaking these 

 bowlders open can the purer white iolite be obtained. This, 

 however, is not entirely free from alteration, for it shows a 

 thin silky to micaceous coating and shows internally minute 

 scales of mica (biotite ?), which lie parallel to the basal plane. 

 The rhodolite garnet is the only mineral as yet identified as 

 occurring directly with the iolite, but staurolite, cyanite, pale 

 green apatite and rutile seem to be present. The minute 

 inclusions of mica give rise to a beautiful golden sheen when 

 the iolite is viewed in the direction of the vertical axis in 

 reflected light, thus promising a new chatoyant gem. 



.No crystal planes have been observed, the mineral being 

 columnar and varying from 3 to 25 mm in diameter and length. 



The color is pale yellow to greenish yellow. The mineral is 

 nearly transparent but is wholly devoid of dichroism, so emi- 

 nent a characteristic of the species. The analysis by Basker- 

 ville identifies this mineral as iolite. 



The result of the analysis is as follows : 



Specific gravity = 2*54 



Ratio. 



Si0 ._ 47-60 -793 = 9'00 



A1 2 3 36-20 -354 = 4'01 



FeO 2-13 -015) . 



MgO 10-73 -268 f Jbd - 6Zl 



CaO trace 



H 2 3-14 -174 = 1-98 



99-80 



