256 The American Geologist. October, 1905. 
The cavities in the Willamette meteorite are in accord with 
it. 
Further, the minerals that form the stony parts of iron 
meteorites (and the same is true of stony meteorites) are 
particularly susceptible to oxidation and total decay. That 
is probably the reason that by far the larger number of 
meteorites which have been found, without any knowledge 
of the date of their falling, are irony meteorites, while by 
far the larger number of those which have been seen to fall 
are stony meteorites. If this ratio has prevailed through- 
out past ages, it argues that the stony meteorites have 
rotted. It has even been suggested that all or many of the 
irony meteorites that have been found are merely the iron)' 
remnants of former stony meteorites which have other- 
wise rotted and been converted into soil. The mineral 
olivine is one of the most easily changed silicates, a fact 
familiar to all petrographers. It has contributed largely 
toward the serpentinous greenstones. Its easy decay loos- 
ens and promotes the alteration of the other associated min- 
erals. It is a very abundant mineral in nearly all irony 
meteorites. Troilite is a sulphide of iron. It is easily oxi- 
dized, and gives rise to sulphuric acid which powerfully at- 
tacks everything adjacent. We do not know what were the 
minerals that originally filled these cavities, but that they 
embraced both olivine and troilite is' highly probable. 
Microscopic examination, according to Mr. H. L. Preston 
(quoted by Dr. Ward), discloses that ''there are numerous 
small troilite nod.ules from one to three millimetres in size 
scattered promiscuously throughout the section, and a few 
rod-shaped ones one millimetre in width and in some in- 
stances up to fifteen millimetres in length. The largest 
troilite nodule found in several sections was twenty-eight 
millimetres in diameter." This strongly indicates that one 
of the chief minerals originally in these cavities was trolite, 
and it may have been the only mineral. 
If this explanation of these cavities be correct, it is 
reasonable to expect that in case a meridional section of the 
mass is ever made it will disclose some large roundish 
masses of troilite, which is very likely to be associated with 
some silicate minerals. 
