New Occurrence of Rutile and Sapphirine. 269 



They are of a pale, dull green color and as a rule are 

 definitely orientated with reference to the enclosing crystal. 

 Just what the orientation is has not been made out. Many 

 of the spinels have a highly perfect octahedral habit, the 

 whole crystal coming into view with slight changes of 

 focus. Other crystals show the characteristic cross-sections 

 of distorted octahedrons, or form flat, triangular plates. These 

 attain a diameter of ■015 mm , though usually smaller. Again 

 the spinels have the habit of relatively greatly elongated rods, 

 or somewhat flattened blades arranged in lines across the feld- 

 spars. The inclusions are isotropic, although being wholly 

 enclosed in the feldspar, which often exhibits a slight disturb- 

 ance in its optical properties about the inclusions, they often 

 seem to be slightly doubly-refracting themselves. Minute 

 inclusions of sapphirine have also been noted occasionally 

 associated with the spinels, but these have a different color and 

 are irregular in outline. 



The feldspars are an andesine like that of the anorthosite. 

 They are as a rule quite evenly distributed and of fairly uniform 

 size comparable with the ilmenite, but occasionally, as noted, 

 they become more numerous and of larger size, and form groups 

 of grains. Many of them show evidences of strains and slight 

 bending. In even the fresher material collected the feldspar 

 is usually partly replaced by secondary products, particularly 

 where biotite and sapphirine were present with it, and in more 

 highly altered specimens it is entirely gone. 



The biotite is sometimes quite abundant and .has the same 

 characteristics as previously described. It is most intimately 

 associated with the plagioclase, and where sapphirine is present 

 it appears to have developed later than this mineral. Its 

 position about the margins of the feldspar, or replacing part of 

 it is here, as elsewhere, strongly suggestive of a later second- 

 ary origin. Its alteration is to chloritic products. 



An occasional grain of apatite has been noted, but it is 

 hardly present as more than a trace. 



The sapphirine, which is of especial interest here, it being 

 not only a new occurrence of this rare mineral, but also in a 

 new association, seems to be confined to portions of the 

 ilmenite rock which carry rutile. Even when alteration has 

 destroyed both plagioclase and sapphirine, the characteristic 

 alteration products enable it to be seen that the sapphirine has 

 been a quite constant associate of the feldspar in the rutile- 

 bearing portion. That there is some intimate relation be- 

 tween the feldspar and the sapphirine is shown by the fact that 

 the latter generally lies between the feldspar and the ilmenite. 

 It is often seen as a narrow band extending around the feld- 

 spar. (See fig. 1.) The band may widen out into a larger 



