New Occurrence of Rutile and Sapphirine. 267 



state, separated, forming the intergrowth described. Such a 

 change may have been considerably facilitated by the meta- 

 morphism to which this rock has to some degree been sub- 

 jected. It is to be noted that, although the two minerals 

 have very nearly the same crystallographic constants, they 

 differ somewhat in symmetry, and the accepted formulae for 

 the two are not strictly analogous, ilmenite being RTi0 3 and 

 hematite Fe 2 3 . It may, therefore, be questioned whether the 

 crystallographic and chemical analogies of the two are suffi- 

 ciently close to permit of isomorphous mixture to more than a 

 very limited degree, but close enough to condition an intimate 

 and definite crystallographic intergrowth. It is hoped that a 

 further study of the relations existing between ilmenite and 

 hematite and also magnetite when these molecules occur 

 together may soon be carried out. 



Deposit with Riilile-Sapphirine- Bearing Ilmenite. — The 

 second, and in the present instance, the most interesting 

 deposit, is located near the top of the same ridge as the pre- 

 vious one, about one-half a mile to the southwest. It has been 

 pretty well exposed for a length of about 300 feet and for 50 

 feet in width. At one point the ilmenite rock has been opened 

 up to a depth of about 15 feet and to a less depth in several 

 others. Its contacts with the anorthosite, where exposed, have 

 a roughly east and west trend and are nearly vertical. In the 

 ore are several streaks of anorthosite which have also a nearly 

 vertical extension and a more or less marked schistosity follow- 

 ing much the same direction. There is also in the ore in 

 places a feebly marked banding with the same trend. Further 

 west and southwest of this deposit several small dike-like 

 masses of ilmenite are exposed with the same orientation, but 

 these carry no rutile, etc. 



The mineralogical character of the greater part of the ilmen- 

 ite rock in this mass is essentially the same as that previously 

 described. The grain, however, appears on the average to be 

 a little finer. A portion of the deposit differs from the rest 

 and from other known bodies of ilmenite associated with anor- 

 thosite rocks, in containing a notable percentage of rutile and a 

 smaller amount of the rare mineral sapphirine. 



The rutile-bearing portion was first observed as a streak two 

 feet wide, with a nearly vertical dip and an indistinctly marked 

 banding parallel to the walls which ran east and west. The 

 passage of this streak into the rutile-free ilmenite on both sides 

 was very sudden. Toward the west the rutile-bearing portion 

 widened, and was somewhat less sharply defined, and there is 

 evidence which points to the occurrence of rutile-bearing bands 

 and patches. It appears, however, to always change quite 

 sharply into the rutile-free rock. It was traced for several hun- 

 dred feet. 



