H. 8. Washington — Jerome Meteorite. 449 



(ckb)," * though I have no sections of either of his two ex- 

 amples for comparison. It will be remembered that it resem- 

 bles megascopically the less fresh parts of one of these, the 

 Bluff meteorite. 



The chondrules of bronzite run up to nearly 2 mm in 

 diameter, and show, in most cases, circular sections, or nearly 

 so, though angular and fragmental forms are seen. They 

 present the usual fibrous, eccentrically radiated structure. 



The olivine chondrules are somewhat larger, up to 3 mm 

 and show greater variety. Many are monosomatic, with par- 

 allel plate structure and border as figured by Tschermak. f 

 The interstitial matter here is granular, colorless and isotropic, 

 containing small, black, opaque particles. It is possibly a glass, 

 as in the cases described by Tschermak, though its pronounced 

 granular character is against this view, and points rather to the 

 idea that it is maskelynite. These chondrules are usually 

 small and round. 



Porphyritic olivine chondrules are more numerous, as well 

 as the largest in size, and are occasionally rounded, but usually 

 irregular in outline. They consist of oblong grains and crys- 

 tals (showing traces of pinacoids and domes) of colorless oli- 

 vine, lying pellmell in a gray or colorless, finely fibrous ground- 

 mass. This is formed of patches of straight narrow fibers par- 

 allel over small areas, each small area extinguishing as a unit, 

 but unlike those adjacent, where the fibers run in another 

 direction. It was supposed at first that these thin color- 

 less rods were a rather basic plagioclase, since they extinguish 

 at various angles up to 20° with their long axes, and their 

 polarization colors are grays and pale yellows. Close examina- 

 tion under high powers, however, revealed the fact that in 

 many places there is no break in continuity between the fibers 

 and distinct adjacent olivine crystals, and that in these cases 

 both crystal and fibers extinguish simultaneously. They must, 

 therefore, be referred to olivine, and the apparent oblique ex- 

 tinction is due to the fact that the fibers project obliquely 

 from the surface of the olivine crystal, seemingly in the direc- 

 tion of a domal or prismatic plane. That they are rods and 

 not plates (as in the preceding type of chondrules) is shown by 

 their sections in certain places, where they present the appear- 

 ance of small rounded grains. Such skeletal development is 

 a not uncommon feature of olivine, as is well known. 



Other porphyritic chondrules are seen in which olivine crys- 

 tals and fragments are embedded in a fine-grained mosaic of 

 olivine and enstatite grains. One peculiar ovoidal chondrule 

 was observed, composed of a long, seemingly corroded, olivine 



* Brezina, Ann. k. k. Nat. hist , Hofmuseums. x, 261, 1895. 

 % Tschermak, Mikr. Besch. d. Meteoriten, pi. x, 2. 



