WARREN" AND PALACHE. — QUINCY PEGMATITES. 



165 



Figure 8. 



formation and is particularly associated with aegirite, as embedded 

 xenomorphic plates, and groups of tiny crystals implanted on crevices 

 of fractured aegirite crystals (Ballou quarry), and as clusters of 

 larger crystals upon the walls of cavities left by the destruction of 

 such crystals by magmatic resorption (Fallon quarry). The crystals 

 are small, not exceeding 



a diameter of 2 mm. and |f-~~->__ C 



are always very thin 

 tabular in habit. A dull 

 black coating of manga- 

 nese oxide commonly 

 gives them a lustreless 

 appearance, but in two specimens brilliant crystals were obtained which, 

 despite minute size, gave good measurements on the goniometer. 

 Octahedrite is almost always sparingly present with ilmenite. 



The forms observed are as follows: c(OOOl), m(lOTO), a(ll2o), 

 5(2130),* ^ (10T9), u(10T4), f (2025), r(lOTl), f(0. 7.7.20), e(0lT2), 

 A(04?5),* s(022l), X(05o2),* g(0.3.3.11),* k(0.3.3.10),* 7r(ll23), 

 n(2243). (* New forms.) 



The crystals from Ballou quarry showed the forms c, m, a, 8, r, and tt, 



the prism zone being well de- 

 veloped and the base large and 

 very brilliant. The prism is 

 new to ilmenite. Figure 8. 



Crystals from Fallon quarry 

 are dominantly rhombohedral, 

 prism faces being reduced to mere lines. The crystals measured 

 showed the following combinations : 



1. c, 8, r, f, e, s, n. 



2. c, m, 0, i, r, k. ' 



3. c, m, 6, r, u, e, k, tt, n. 



4. c, m, 6, r, n. 



5. c, 0, $, r, e, g, A, \, n. 



6. c, m, 6, i, r, e, A, k, n. 



7. c, u, r. 



As shown in Figure 9, flat positive rhombohedrons are largely de- 

 veloped on these crystals, recalling the description of one (the common) 

 phase of " Crichtonite " from Oisans by Descloizeaux.^^ That author 

 considered the rhombohedrons which he measured, (10T5)and (10T9) 



Figure 9. 



" Mineralogie, 2, 222 (1893). 



