METEORITE FROM CASTRAY RIVER. 49 



3. Aerolites^ or meteoric stones, (consisting generally 

 of one or more silicates, interspersed with 

 isolated particles of nickeliferous iron, troilite, 



&c.y.* 



It is estimated that about one-third of the known 

 elements have been detected in the various forms of 

 meteoric substances, manj in their free state, but by far 

 the greater number as homogeneous mineral species in 

 the condition of alloys, oxides, sulphides, silicates, phos- 

 phides, and hydrocarbons.f Of the somewhat large 

 number of compounds which have been recognised and 

 described, about 12 species are unrepresented among the 

 terrestrial minerals. 



Of the meteorites recorded from Australia, 22 are 

 classed as belonging to the first, or siderite section, seven 

 to that termed siderolites, and one doubtfully belonging 

 to the aerolites. 



That already recorded from this State, as well as the 

 one now described, belong to the siderite or nickeliferous- 

 iron section. 



A noted peculiarity of the metallic ingredients in thin 

 section is the development of the " Widmanstatten " 

 markings on a polished surface being exposed to the 

 action of acids or bromine, owing to the inequality of 

 action on the various alloys of nickel and iron. 



Details oj Specimen. 

 Castray Meteorite — 

 Type : Siderite. 

 Weight : 51 grs. 

 Size: Length, 18 millimetres; greatest breadth, 



10 milUmetres. 

 Locality : Castray River, North-West Tas- 

 mania. 



The specimen is dark, almost black, with the charac- 

 teristic smooth, almost graphitic, surface glimmer 

 common to this class of meteoric substances. In shape 



* Introduction to the Study of Meteorites. (British Museum, 1896.) 

 f The discovery of undoubted diamonds in the numerous masses of 



meteoric iron found in the Canyon Diable. America, was announced in the 



Ameyican Journal of Science, July, 1891. 



