THE CRANBOURNE METEORITES 
33 
Occasionally a pinkish-brown mineral is intercalated with bands 
of limonite. It is isotropic and inert to etching reagents. The 
powder obtained with the micro-drill is distinctly magnetic, and 
yields positive tests for iron and nickel. The mineral is regarded, 
therefore, as trevorite. 
The limonitic scale of the Cranbourne No. 4, No. 5 and No. 7 
irons contains numerous quartz grains, and such grains have been 
recorded in the scale of Cranbourne No. 2 (Walcott, 1915). Both 
rounded and angular grains occur, imbedded in the scale to a 
depth of two or three inches. They apparently represent sand 
which has been blown against the meteorite, and adhered to it 
during the process of oxidation. The depth at which the quartz is 
found is some measure of the expansion that takes place during 
the oxidation and hydration of the iron. 
Oxidation of the Cranbourne Irons 
With the exception of the Cranbourne No. 2 iron, all these 
meteorites show a pronounced tendency to oxidize and scale, so 
that they are extremely difficult to preserve. The Cranbourne 
No. 1 iron in the British Museum is kept in an atmosphere of 
nitrogen on this account; and the Cranbourne No. 8 iron, in the 
Geological Survey Museum, Melbourne, is preserved in a bath of 
kerosene. 
Oxidation is partly due to the composition of the irons, which 
contain insufficient nickel to enable them to resist rusting. The 
rapidity and depth of oxidation appears, however, to be connected 
with the presence of unusual amounts of chlorine (in the form of 
chlorides) in the interior of the meteorites. A freshly polished 
surface of iron, whether large or small, very soon exudes numerous 
droplets of ferrous chloride along the junctions of kamacite bands, 
along cracks, and at the junctions of nodules with the metal. 
One such prepared surface, 4 5 X 3 5 inches, developed strings 
of minute globules after standing overnight, and even when the 
specimen was immersed in kerosene, the globules continued to 
grow in size. As long as the specimen was maintained in kerosene, 
the liquid of the globules was prevented from attacking the iron, 
and when the specimen was tilted, the larger globules rolled off its 
surface. When, however, the surfaces of such specimens are left 
exposed to the atmosphere, the globules etch the polished surfaces 
and completely destroy the polish within a few days. 
The globules are at first almost colourless and consist of ferrous 
chloride. On exposure to air they become yellowish and then 
brown as the ferrous chloride oxidizes to ferric chloride, which 
attacks the iron. After two or three days the ferric chloride 
