4 BULLETIN 94, UNITED STATES NATIONAL MUSEUM. 



9. Orvinite (Co) : A small group consisting of chondrules in a 

 blackish ground, showing a fluidal structure. It has at present but 

 one representative. 



10. Tadjerite (Ct) : Consisting of a dark, for the most part half 

 glassy ground containing chondrules. 



11. Ureilite (Cu) : Consisting essentially of olivine, with sometimes 

 chondritic and sometimes granular structure, of a dark, nearly black 

 color, and often showing transition stages into the next class. 



II. Stony-Ieon Meteorites : Sidekolites. 



Meteorites consisting of silicate minerals in a more or less discon- 

 nected mesh or sponge of nickel-iron. 



1. Lodhranite (Lo) : Consisting of a crystalline granular mixture 

 of olivine and bronzite in a fine, more or less disconnected network or 

 sponge of metal. 



2. Mesosiderite (Grahamite) (M) : Consisting essentially of oliv- 

 ine, bronzite, plagioclase, and augite, sometimes chondritic, sometimes 

 crystalline granular, in a more or less interrupted network or sponge 

 of metal. 



3. Siderophyre (S) : Consisting essentially of bronzite and nickel- 

 iron with accessory asmanite in a network of nickel-iron of octahedral 

 crystallization and showing Widmanstatten figures. 



4. Pallasite (P) : Consisting of olivine in a continuous network or 

 sponge of metal. 



5. Meteoric iron breccia (Obc) : Meteorites consisting of crystal- 

 line chondrules in a breccia-like mass of octahedral iron. 



6. Meteoric iron of Netschaevo (Omn) : Meteorites consisting of 

 crystalline chondrules in a mass of octahedral nickel-iron. 



III. Nickel-Ikon Meteorites : Siderites. 



Meteorites consisting essentially of nickel-iron with iron sulphide 

 and phosphide and usually graphite or other form of carbon. 



1. Octahedral irons: Consisting essentially of nickel-iron alloys 

 arranged in the form of plates parallel with the faces of an octa- 

 hedron, and often interlaminated with thin plates of schreibersite. 

 On etching with acid they show Widmanstatten figures. According 

 to the thickness of the plates they are divided as follows: (a) 

 Octahedral irons with lamellsB 0.1 mm. in thickness (Off) ; (6) octa- 

 hedral irons with lamellae 0.15 to 0.4 mm. in thickness (Of); (c) 

 octahedral irons with lamellae 0.5 to 1 mm. in thickness (Om) ; (d) 

 octahedral irons with lamellae 1.5 to 2 mm. in thickness (Og) ; (e) 

 octahedral irons with lamellae over 2| mm. in thiclmess (Ogg) ; (f) 

 breccia-like octahedral irons (Obz). 



