OBSERVATIONS OP LUMINOUS METEORS. 18'J 



first sight the appearance of "very finely crystallized troilite ;" closer inspec- 

 tion, however, reveals the fact that most of these nodules have more or less 

 of a Mack mineral associated with them. This substance was ascertained to 

 he — not graphite, as might at first sight have been supposed,- — hut chromium 

 monosulphide, a mineral new both to terrestrial and celestial mineralogy. 



Daubreelite, as Dr. Smith has named it, is a black lustrous mineral, highly 

 crystalline, usually occurring on the surface of the nodules of troilite, but some- 

 times traversing them ; in one nodule a vein of the mineral, 2 millims. wide 

 and 12 millims. in length, crosses the very centre of a nodule. It exhibits 

 a distinct cleavage, is very fragile, and is feebly magnetic : the powdered 

 mineral is perfectly black and is but slightly acted upon by strong acids, with 

 the exception of nitric acid, in which it completely dissolves : this reaction 

 serves to distinguish and separate it from chromite. The mineral has not yet 

 been completely analyzed; one hundred milligrammes were examined and 

 found to contain 36-48 per cent, of sulphur, the remainder being chromium 

 with nearly ten per cent, of iron and a little carbonaceous matter. (Chromiun 

 monosulphide contains chromium = 62-38, and sulphur = 37*62 ; iron- 

 monosulphide troilite contains iron = 63-64, and sulphur = 36-36.) The 

 discovery of this new body is of great interest in extending the knowledge 

 already arrived at by aid of the spectroscope of the distribution of chromium 

 in cosmical bodies. 



Foirnd about 1850. — Pittsburg, Alleghany Co., Pennsylvania*. 



This large mass of meteoric iron, weighing 132 kilog., was turned up by a 

 plough at Pittsburg. It was briefly described at the time by Silliman, and 

 has now been analyzed by Dr. Genth. The specific gravity appears to bo 

 7-741 ; and the chemical composition of a somewhat oxidized specimen was 

 found to be 



Iron 92809 



Nickel 4-665 



Cobalt 0-395 



Copper 0-034 



Manganese 0-141 



Sulphur 0-037 



Phosphorus 0-251 



98-332 



Tho phosphorus corresponds with about 1-8 per cent, of Schreibersite. The 

 iron, when etched, exhibits "Widmannstattian figures, and the presence of mi- 

 nute crystals of a phosphide coidd be recognized on the surface of the section. 



Found 1870. — Ovifak, Disko, Greenlandf. 



M. Daubree gives the name Lawrencite to the iron protochloride, the presence 

 of which he has detected in the curious meteoric irons of Ovifak. It was 

 earlier recognized in the Tennessee meteoric iron by Dr. Lawrence Smith. 



Found August 1873. — Duel Hill, Madison Co., N. Carolina*. 

 A mass of meteoric iron was found in August 1873, on the land of Mr. 



* F. A. Genth, 'Amer. Journ. Be.' 1876, vol. xii. p. 72. Eeport of Geological Survey 

 of Pennsylvania, 1875. 



t G. A. Daubree, ' Compt. Bend.' 1877, January 8th, vol. lxxrdv. p. 06. 

 { B. S. Burton, ' Amer. Journ. Sc' 187<>, vol. xii. p. 43«. 



