HANDBOOK OF THE METEORITE COLLECTIONS. 



11 



Oshomite. — This name is also one of Maskelyne's proposal. The 

 mineral occurs in golden yeMow microscopic octahedra, associated 

 with the oldhamite in the Busti meteorite. Crystals are brittle and 

 insoluble in acids, even resisting the fluxes potassium and sodium 

 carbonates. Composition uncertain, but regarded as a titanium or 

 zirconium oxychloride. 



Pyroxenes. — Pyroxene is common in meteorites in both orthorhom- 

 bic and monoclinic forms. 



1. Orthorhombic pyroxenes: enstatite and bronzite. These min- 

 erals, next to the olivines, are the most common of the meteoric sili- 

 cate minerals. The composition is somewhat variable, owing to the 

 varying proportions of iron and magnesia, as in the olivines. A typi- 

 cal enstatite corresponds to the formula MgSiOa, but through the 

 assumption of iron this passes over into the bronzite variety (MgFe) 

 SiOg. So far as known, the highly ferriferous and pleochroic vari- 

 ety, hypersthene, never occurs in meteorites, though in at least one 

 instance — that of Shalka, India — the percentage of iron is fully as 

 high as in strongly pleochroic hypersthene. The name clino-enstatite 

 has been given to a monoclinic variety with a smaller extinction angle 

 on clinopinacoidal sections than other monoclinic pyroxenes, and 

 which is characterized further by a marked tendency toward polysyn- 

 thetic twinning. The varying composition of enstatite and bronzite 

 from some of the best known meteorites is given below : 



« Smith, J. L., Amer. Joum. Sci., vol. 38, 1864, p. 225. 



• Maskelyne, Philos. Trans. Roy. Soc. London, voL 160, 1870, p. 206. 

 8 Tschermak, Sitz. Akad. Wiss. Wien, vol. 61, 1870, p. 467. 

 iMaskelyne, Philos. Trans. Roy. Soc. London, vol. 161, 1871, p. 359. 

 ' Rammelsberg, Monatsber. Akad. Berlin, 1870, p. 314. 



• Borgstrom, Bull. Coram, geol. Finlande, No. 14, 1903. 

 » Teclu, Rammelsberg's Mineralchemie, 1875, p. 382. 



• Meunier, Ann. Chem. Phys., vol. 17, 1869, p. 12. 



» Rammelsberg, Monatsber. Akad. Berlin, 1870, p. 319. 

 w Winkler, Cohen's Meteoritenkunde, Heft 1, 1894, p. 281. 



As with olivine, the mineral rarely occurs in good crystal form, 

 excepting in the porphyritic chrondrites. A more common form, as 

 noted later, is in that of radiating and cryptocrystalline kugels. 



