Crystallization of Parisite. 



555 



The presence on one crystal of the form/, observed before 

 only by Solly on a Binnenthal crystal, confirms this form. All 

 the forms present gave angles agreeing very closely with the 

 values calculated from the axial ratio of Koksharow as used 

 by Dana. 



Chemical tests on the ilmenite from both quarries revealed 

 strong qualitative reactions for manganese ; an analysis would 

 be interesting, but it was not possible to separate enough of 

 the fresh mineral for this purpose. 



Octahedrite. — Octahedrite is found chiefly in the large cen- 

 tral pocket of the Fallon pegmatite, generally in close associ- 



Fig. 10. 



Fig. 11. 



ation with aegirite and often formed posterior to the alteration 

 of that mineral, since it is not infrequently seen on the walls 

 of hollow casts of aegirite crystals associated with fluorite and 

 ilmenite. Isolated crystals were also found implanted on feld- 

 spar crystals. The crystals of octahedrite are small, of a deep 

 black color, and of very brilliant luster. They show only the 

 forms <!(001), m(llO), p(lll), £(112), and s(113), the two last 

 the least common. These crystals are marked by two pecu- 

 liarities ; they are in large part of prismatic habit with the first 

 order prism dominant, a habit not before described for this 

 mineral, and causing the crystals to be at first mistaken for 



