466 
PETROLOGY: G. P. MERRILL 
Proc. N. a. S. 
I can learn from the descriptions given by other writers, that the pecuHar 
saucer-shaped depressions (fig. 4, p. 452 and fig. 5, pi. 1) which were surely 
formed at the time of solidification are limited to the cryptocrystalline 
and radiated enstatite types. They are never found in the polysomatic, 
porphyritic and holocrystalline forms although these may be of like min- 
eral composition. The cause of this cannot then be chemical. It would 
^seem fair to assume that it was fundamental and due to their origin under 
quite different conditions. 
FIG. 17 
Chondrule-like blebs of metallic iron in furnace slag showing, in some instances, 
depressions similar to those of the enstatite chondrules in meteorites. The white point- 
ers mark some of the more prominent forms. 
Concerning the origin of these depressions and indeed as bearing upon 
the general subject of chondritic formation, it may be well to add inci- 
dentally that in a fragment of furnace slag received from Lawrence County, 
Tennessee (exact locality unknown), I find abundant beautifully spherulitic 
chondrules of metallic iron embedded in the glassy slag. These are from 
one to three mm. in diameter and often so densely crowded as to have 
mutually interferred so that when separated there is left on one of them 
a concavity similar to that of the enstatite chondrules. Indeed the simu- 
lation of exterior form is almost perfect (see fig. 17). If, however* 
