198 BASALT. 



Of these the first formed the principal portion of the stone. It is traversed by number- 

 less fine fissures parallel to the cleavage. It is of a grayish-browu color, anisotropic, and 

 shows only feeble pleochroism. In cleavage and optical characters it is similar to diopside. 

 It is quite commonly twinned. While the mineral is regarded as augitic, Tschermak 

 thinks, from its chemical composition, that it is different from any terrestrial compound. 



The second mineral possesses conchoidal fracture, and is inclosed in and subordinate to 

 the augitic mineral. Its form is that of a distorted cube. Tlie hardness is a little less 

 than that of orthoclase, while its cliemical composition is similar to that of labradorite. 

 Tschermak proposed for it the name maslcchjnite. The tliird mineral is intergrown witii 

 the first, is traversed by parallel fissures, and is orthorhombic in crystallization. It is 

 referred to bronzite (enstatite). 



The Iburth mineral lies between the other minerals or is inclosed in the mashclynite. 

 It is pitch-black, semi-metallic, with a- conchoidal fracture, black streak, and is strongly 

 maf'uetic. This mineral is regarded as magnetite. The fifth mineral is referred to 

 pyrrhotite. The section as figured by Tschermak resembles some of the gabbros.* 



Later, Tschermak speaks of tlie brownish mineral as augite, and of the maskelynite as 

 a glassy state of plagioclase.f 



PdwloivJca, 8ardton\ Russia. 



This meteorite has been described by Mr. Th. Tschernyschow, as composed of a 

 brittle ash-gray groundmass, formed by a crystalline-granular mixture of feldspar, ensta- 

 tite, and diallage, holding porphyritic grains of these minerals and olivine. The feldspar 

 shows polysynthetic twinning, and is referred to anorthite. It is in irregular and ledge- 

 formed masses. The diallage is either colorless or brownish-gray, with cleavage planes, 

 and an absence of dichroism. The enstatite shows a fine parallel cleavage striation, and 

 holds chromite (?) in black grains arranged parallel to the cleavage lines. Sometimes the 

 feldspar predominates, and at others the pyroxenes ; and of the latter, sometimes the 

 enstatite and sometimes the diallage is most abundant. 



The olivine occurs in clear-green grains. Besides the above minerals, there were seen 

 also nickeliferous iron, pyrrhotite, and cliromite, in grains and crystals. It also contains 

 the cloudy-gray friction-product of Tschermak, but which tlie present writer regards as a 

 base. % 



This meteorite is placed, from the above description, with the basaltic metet)rites, 

 although the entire correctness of the microscopic diagnosis is perhaps questionable. 



Le Teilleul, Ifunche, France. 



This meteorite, according to Daubree, is composed of plagioclase (anorthite), enstatite, 

 diallage, olivine, iron, pyrrhotite, and chromite. 



The feldspar is colorless, twinned, and presents similar inclusions to those found in the 

 feldspar of gabbro. On chemical tests tlie feldspar is referred to anorthite. The enstatite 

 shows two cleavages, is of a pale-greenish color, and contains opaque inclusions. Tlie 

 diallage is of a darker color than the enstatite, and contains inclusions of oxide of iron or 

 troilite, as well as other forms similar to those common in diallage, and arranged parallel 

 to cue another. The olivine is colorless. § 



* Sitz. Wicn, Akad., 1S72, Ixv. (1), 122-135; Mlii. Mittli., 1872, pp. 87-05. 



f Die mikro.s. Bcsch. dcr Mctcoritcu, 1S83, i. 7. 



X Zeit. Deut. gcol. Gesells., 1883, xxxv. 100-192. 



§ Comptes Eendus, 1S79, Ixxxviii. 514-547; Neues Jahr. Min., 1S79, pp. 905, 906. 



