Mar., 1905. The Rodeo Meteorite — Farrington. 3 



meter in diameter, of a black, amorphous, friable substance resem- 

 bling graphite. The form of the nodule in the direction of the section 

 is nearly circular, but in the third dimension its extent is unknown, 

 as it penetrates into the main body of the meteorite, which has not 

 yet been cut. No band of swathing kamacite surrounds the nodule, 

 it being set bodily into the mass of the iron. In appearance and 

 physical properties the substance of the nodule resembles graphite 

 fully, but it is magnetic and fuses in the reducing flame at about 4. 

 Mixed with potassium nitrate it deflagrates readily, but throws out 

 incandescent sparks in addition to the flaming usual to graphite. 

 Potassium carbonate results from the reaction. Oxidation with sul- 

 phuric and chromic acids according to the French method* affords an 

 appreciable quantity of CO 2. On heating in oxygen the substance 

 glows and becomes of a red-brown color. It was found to be little, if 

 any, attacked by the ordinary acids. After a long treatment with aqua 

 regia, however, and addition of ammonia to the solution, a slight pre- 

 cipitate of iron hydroxide was obtained. When powdered and added to 

 a copper sulphate solution, copper was reduced by the substance. Its 

 specific gravity (obtained by Thoulet's solution) was 2.38. -On account 

 of the above properties it would appear that the substance is chiefly 

 graphite, but contains in addition some form of iron, probably a 

 carbide, intimately mixed with it. Such a mixture should exhibit 

 the properties of magnetism, reduction of copper from copper sul- 

 phate and insolubility in acids, which are possessed by this substance. 

 Such properties seem not to have been possessed by graphite which 

 has been described from other meteorites. It is common for meteoric 

 graphite to be accompanied by troilite, as has been noted by Smithf 

 and other authors. The Rodeo graphite, however, seems to contain no 

 troilite. A specimen labelled graphite in the Museum collection of what 

 is probably a portion of a "salamander" from the Isabella Furnace, 

 Etna, Pennsylvania, was found to exhibit properties much like those 

 of the Rodeo graphite except that it is heavier, the specific gravity 

 being 5.56, and the structure is foliated rather than compact. 

 Since a "salamander" originates by the accumulation of graphite 

 and graphitic substances in smelting operations, it seems reasonable 

 to suppose that the Rodeo nodule is a similar segregation of graphite 

 originally more or less disseminated in the iron. 



An analysis of the meteorite was made by Mr. H. W. Nichols, 

 of the Department of Geology of the Museum. Material for analysis 

 was secured by drilling a half-inch hole to a depth of seven-eighths 



* Blair, The Chemical Analysis of Iron, third edition, p. 136. 



t Am. Jour. Sci. 3, 2, p. 304, 433. 



