so 
Keith R. Miles. 
Comparison of these figures tends to bear out the impression that the 
specimens examined by the author contain appreciably more iron oxide 
(probably in the form of iron ores) than the average nodules from Cook’s 
Deposit but it is interesting to note that probably all iron oxide, alumina, 
potash and magnesia shown in the chemical analysis of the composite sample 
can be accounted for by the glauconite, iron ore and felspar in the nodides them- 
selves. 
THE PHOSPHATISED WOOD. 
An examination was made of thin slices of three specimens of phos- 
phatised wood. Some of this materia] was figured and described by Simpson 
in 1912 (4). The “wood” itself is now completely replaced by phosphatic 
material optically and microscopically indistinguishable from the collophanite 
(which Simpson regarded as fluorapatite) matrix of the nodules described 
above except that in most cases the minute structures of the original woody 
tissue have been perfectly preserved. The wood has been identified as a 
Mesozoic conifer classed as Cedroxylon (4). 
Of interest in the present investigations is the fact that all the specimens 
examined are abundantly riddled with tunnels and pipes filled with phosphatic 
material which appears identical in composition with the phosphatic nodules 
already described. These tunnels are considered to have been made by 
boring organisms in the original wood. Specimens of wood examined ranged 
from If inches to 3 inches in diameter and were up to 3i inches long. The 
borer holes are up to about 0-35 inch in diameter and often run the full length 
of the wood specimen. 
Under the microscope the material filling these borer holes is seen to consist 
essentially of detrital quartz and felspar, and abundant glauconite with rare 
scattered fragments of black opaque iron ore (? magnetite) set in a matrix 
of collophanite similar to that found in the phosphate nodules. Some second- 
ary limonite was seen in the more weathered specimens but was completely 
absent from the freshest specimen examined. 
The quartz in this material is fine and even grained, seldom more than 
0*5 mm. in diameter. The felspar includes fragments of microcline, ortho- 
dase and twinned plagioclase, probably oligoclase. Detrital zircon is a rare 
accessory. In addition to the above, the borders of several borer holes were 
marked by clusters of tiny spherical brown bodies. These have already 
been noted by Simpson (op. cit .) and considered to be the fossil excreta of 
wood boring beetles. 
No attempt was made to measure the relative proportions of the com- 
ponents of the filling material in these borer holes, but from a visual inspection 
the writer considers that although the iron ore content is probably less than 
that of nodule A described above, the average glauconite content is at least 
as high as in nodule E and is probably between 15 to 20 per cent. The pro- 
portion of quartz to felspar is probably about 10 . 1. 
It is interesting to note therefore that even in specimens of phosphatised 
wood, which from Dandaragan is a source of high grade phosphate, there is 
a certain amount of deleterious material (iron oxide and alumina) present 
in the form of minerals occurring as filling material for the numerous borer 
holes within the wood. 
