168 Dr. Walter Flight— On Meteorites. 



boundary of the Desert near El Para. There is, moreover, some 

 account of a mass yet vaster to be seen in the very centre of the 

 desolate region. In this district alone not less than 15,000 kilo- 

 grammes in weight of meteoritic masses have been discovered. 



While examining sections of two of the above-mentioned masses, 

 Dr. Smith noticed a number of nodular concretions imbedded in the 

 metal, having at first sight the appearance of "very finely crystal- 

 lized troilite " ; closer inspection, however, reveals the fact that 

 most of these nodules have more or less of a black mineral associated 

 with them. This substance was ascertained to be — not graphite, as 

 might at first sight have been supposed, — but chromium monosul- 

 phide, 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 sometimes 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 milli- 

 grammes were examined and found to contain 3648 per cent, of 

 sulphur, the remainder being chromium, with nearly 10 per cent, of 

 iron, and a little carbonaceous matter. (Chromium monosulphide 

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

 phide 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. 



Dr. L. Smith ^ publishes a further paper on the new mineral 

 occurring in the irons, to which mineral he has given the name of 

 daubreelite. It possesses the following composition : — 



Calculated. Found. 



Sulphur 44-29 43-26 



Chromium 36-33 36-38 



Iron 19-38 " 20-36 



100-00 100-00 



It is a sulphide corresponding in atomic constituents to the well- 

 known oxide, chromite (FeO,Cr03), daubreelite being FeS.CrSj, 

 sulphur replacing the oxygen. The calculation of the composition 

 is based upon the sulphur found in the analyses. The finer powder 

 obtained by cutting sections of the irons are treated with a magnet 

 to remove the nickel-iron ; that remaining consists of troilite and 

 daubreelite. This is then digested with strong hydrochloric acid 

 several times ; all the troilite dissolves readily, and the residue 

 consists of the new sulphide. " It consists of shining black frag- 

 ments, more or less scaly in structure, not altogether unlike fine 

 particles of molybdenite." The fracture is uneven, except in one 

 1 Amer. Journ. Sc. 1878, xvi. p. 270. 



