98 PERIDOTITE. 



points on the larger iron masses through the siHcate. These globules are of every size, 

 from those whose metallic lustre and character can he readily recognized with low 

 powers to those remaining a fine dust when magnified one-thousand diameters. It cannot 

 be said that the finer dust-like portions, resembling the globules in the basaltic base, are 

 the same as the larger globules of iron ; but the grndual transition in size between the 

 grains of different sizes, and, with the increase in power, the increase in nmnber of 

 globules that can be recognized as metallic iron leads one to suspect that all these gran- 

 ules, whatever n)ay be their size, are of the same origin and material — iron. These forms, 

 in the minute state, are similar to some of the inclusions in the olivine of the Cumber- 

 land pallasite, but in the latter case the iron, if occurring, woidd be oxidized. Some of 

 the olivine grains show a fine cleavage adjacent to the cross fissures. 



The enstatite is in irregular and oval masses, with a perfect longitudinal cleavage and 

 a cross fracture. The extinction takes place in polarized light parallel to the cleavage. 

 The enstatite contams inclusions of olivine and of iron, the same as previously described 

 in the olivine. 



The diallage has an irregular longitudinal cleavage, its forms being the same as those 

 of the enstatite. The cleavnge lines of the diallage are either cut by irregular cross- 

 fractures, or connect by oblique fissures, so as to give an irregular network over the face, 

 rendering it more obscure and cloudy. The extinction is oblique to the principal 

 cleavage planes. It contains the same inclusions as the enstatite. While the olivine, 

 enstatite, and diallage are all clear, transparent, and colorless in the thin section, yet 

 their cleavage characters are so distinct that in general they can readily be distinguished 

 from one another without the use of polarized light. 



The iron and pyrrhotite are iii detached granules, droplets, irregular jagged masses, 

 and in imperfect sponge-like forms. In some cases they form an irregular net-work in 

 the groundmass, and in an imperfect ring surround the larger grains of olivine, enstatite, 

 and diallage. The material for the above described sections was purchased from W. J. 

 Knowlton of Boston. 



Figure 5, Plate III., represents a central crystal of diallage with the surrounding 

 groundmass of olivine, enstatite, diallage, iron, pyrrhotite, and the ferruginous staining. 



Figure 6, Plate III., shows the semi-sponge-like mass of iron and pyrrhotite with 

 their inclosed silicates, forming a groundmass holding two porphyritic crystals of dial- 

 lage and enstatite, showing their characteristic cleavages and inclusions, although the 

 latter are imperfectly represented. 



Attention was originally called to this very interesting meteorite by Prof. S. F. Peck- 

 ham, who stated that a preliminary examination showed that the metallic portion was 

 an alloy of iron, nickel, and tin. " Full half the mass consists of stony matter which 

 appears in dark-green crystalline masses embedded in a light-gray matrix. . . . Some 

 of the crystalline masses are two inches in thickness, and exhibit distinct monoclinic 

 cleavage. Under the microscope, in thin sections, olivine, and a triclinic feldspar appear 

 to be imbedded in a matrix of pyroxene. ... A small piece of the metal polished 

 and etched exhibited the Widmanstiittian figures very finely."* Prof. C. U. Shepard, in 

 the same volume (pp. 186-188), gives a further description of this meteorite. He writes: 

 " It is marked by the unusual prevalence of clirysolite and meteoric iron, the former 

 probably constituting two-thirds its bulk ; also by the size and distinctness of the 

 chrysolitic individuals, together with their pretty uniform, yellowish-gray or greenish- 



* Am. Jour. Sci., 1879 (3), xviii. 11, 78. 



