HANDBOOK OF THE METEORITE COLLECTIONS. 7 



Chromite and magnetite. — The oxides of chroniium and iron, or of 

 iron alone, are common constituents of terrestrial rocks as well as 

 of meteorites, and need no further mention here other than that they 

 occur as small, usually microscopic disseminated crystals and crystal- 

 line grains. 



Dauhreelite. — In 1876 J. Lawrence Smith gave this name to a black, 

 lustrous, highly crystalline material found by him associated with the 

 troilite in the meteoric irons of Coahuila, Mexico. Incomplete analy- 

 ses made at the time showed 36.48 per cent of sulphur, some 10 per 

 cent of iron, and a little carbonaceous matter, the undetermined por- 

 tion being cliromium. The true composition he announced as being, 

 probably, sulphur 37.62 per cent ; chromium 62.38 per cent.^ Later he 

 was able to isolate the material in larger quantity and greater degree 

 of purity from the Coahuila iron, and in 1878 " he published ncAv analy- 

 ses and descriptions showing the mineral to have the probable com- 

 position: Sulphur, 44.29 per cent; chromium, 36.33 per cent; iron, 

 19.38 per cent ; or the formula FeS Ctj S3. Actual analyses, however, 

 showed: Sulphur, 42.69 per cent; chromium, 35.91 per cent; iron, 

 20.10 per cent; total, 98.70 per cent. 



Feldspars and maskelynite. — From what is known regarding ter- 

 restrial basic igneous rocks, the feldspars of meteorites would natu- 

 rally be assumed to belong to the more basic varieties, as labradorite 

 and anorthite. Not many actual and complete analyses are avail- 

 able owing to the difficulty of securing a sufficient quantity of ma- 

 terial in a fair degree of purity. Those quoted below show that in at 

 least two instances the feldspar is oligoclase, a form characteristic of 

 rocks of intermediate acidity, as the diorites. The name maskelynite^ 

 it should be stated, was given by Tschermak ^ to an isotropic, colorless 

 mineral, abundant in the Shergotty meteorite, and commonly consid- 

 ered a re-fused feldspar. The mineralogist Groth, on the other 

 hand, was inclined to believe it to be a species allied to leucite. The 

 feldspars are common constituents of meteorites of the basaltic types, 

 such as that of Juvinas in France, where they occur in elongated poly- 

 synthetically twinned forms as in terrestrial rocks. In the chondritic 

 types they occur as scattered granules occupying the interspaces of 

 the olivines and enstatites, and often quite lacking in crystal outlines 

 or twinning bands, in which case their satisfactory determination is 

 a matter of great difficulty. In many meteorites of the chondritic 

 type, and in most pallasites, feldspars are wholly lacking. 



» Amer. Journ. Sci., vol. 12, 1876, p. 109. 



« Idem, vol. 16, 1878, p. 270. 



« Sitz. Akad. Wiss. Wlen, vol. 65, 1872, p. 127, 



