1 86 STUDIES FOR STUDENTS 



penetrates into the minutest fissures. Again, the groundmass 

 of the stone of Richmond is a black, half glassy substance which 

 occupies the spaces between the chondri and spreads itself into 

 their interstices. Thus the veins may occur as mere apophyses 

 of a black groundmass. In fact, apparently the same substance 

 forms veins in the meteorites of Mocs, a cement in the stone 

 of Orvinio, and the entire groundmass of such carbonaceous 

 meteorites as Cold Bokkeveld. That the substance is exactly 

 the same in all these cases cannot be regarded altogether 

 proved as yet, however. An analysis by Whitfield of the vein 

 substance of the Bluff meteorite showed it to be very similar in 

 composition to the mass of the stone. Tschermak states that 

 the vein substance of the Goalpara stone consists of a network 

 of iron, holding troilite, carbon, and a glassy substance found to 

 be decomposed by acids. The substance of the black veins of 

 the Chantonnay meteorite Meunier regards as consisting of a 

 silicate of iron. An interesting experiment performed by him 

 in this connection was that of heating meteorites of the group 

 to which he gives the name of Aumalite, to redness without 

 access of air. The meteorite then became black, of lighter spe- 

 cific gravity, and increased in hardness and toughness. In 

 other words, it became a substance which he regards as exactly 

 similar to that of the veins of Chantonnay. He regards the 

 presence of this substance in the stone of Chantonnay, there- 

 fore, as proof that the meteorite had undergone heating or 

 metamorphism before its entrance into the earth's atmosphere. 



So far as the general appearance of the black veins is con- 

 cerned, it may be said with Tschermak that they give the 

 impression that the substance of the meteorite at some time 

 underwent Assuring and that a fused liquid was absorbed into 

 these fissures. The phenomenon must have differed somewhat 

 from that of the injection of fused lava into the interstices of 

 terrestrial rocks, since the substance of the vein mass agrees 

 so closely in composition with that of the substance of the 

 meteorite. 



Vein-like filaments. — In passing from the iron to the stony 



