198 BASALT. 



Of tlicse tlie first formed the principal portion of the stone. It is traversed by nmuber- 

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

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

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

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



The second mineral po.ssesses conchoidal fracture, and is inclosed in and subordinate to 

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

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

 Tscherraak proposed for it the name maskcbjnite. The third minei'al is intergrown with 

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

 referred to bronzite (eustatite). 



The fourth mineral lies between the other minerals or is inclosed in the maskclynite. 

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

 magnetic. This mineral is regarded as magnetite. The fifth mineral is referred to 

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



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

 a glassy state of plagioclase.f 



Pdwloivka, Sardtow, 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 

 eustatite and sometimes the diallage is most abundant. 



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

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

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

 base. J 



Tliis meteorite is placed, from the above description, with the basaltic meteorites, 

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



Le TeiUeul, Manche, 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 the feldspar is referred to anorthite. The enstatite 

 sliows two cleavages, is of a pale-greenish color, and contains opaque inclusions. The 

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

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

 to one another. The olivine is colorless. § 



* Sitz. Wicn. Akad., 1872, Ixv. (1), 122-135; Miu. Mittli., 1872, pp. 87-95. 



f Die mikros. Besch. dcr Mcleoriten, 1883, i. 7. 



X Zcit. Dcut. geol. Gcsells., 1883, xxxv. 190-192. 



§ Comptes Hendus, 1S79, Ixxxviii. 544-547; Neues Jahr. Mia., 1S79, pp. 905, 906. 



