164 
MISCELLANEOUS NOTICES «&<r. 
exposing a piece of 2 , 22 grs. to the flame of the blowpipe 
for some time it retained its dark colour, but lost . Oo gr. or 
about 2 . 7 per cent. It exhibits no trace of lime or iron, and ap¬ 
pears to be almost pure silica deriving its colour from a small por¬ 
tion of carbon. The more carbonaceous portions may be term¬ 
ed , a highly siliceous anthracite, for although proper anthracite con¬ 
tains about twice as much carbon as silica there is no defined li¬ 
mit at which the name ceases to be applicable. Mr. Lyell and 
Dr. Percy retain. the name for a specimen of Worcester anthra¬ 
cite which on analysis by the latter yielded only 2-8 per cent of car¬ 
bon to 68 per cent of ash. 
In several fragments iron pyrites are abundant, occurring either 
in large aggregations or io films, or veins, and occasionally in layers 
alternating with layers of jet. In one specimen, where the woody 
structure is so well preserved that the fibres stand out as we often seo 
them to do in pieces of wood from marshes, some portions are lig¬ 
nite, and others have a peculiar dull glistening golden lustre, which 
is found to arise from the larger fibres having been converted into 
pyrites. Under a microscope this presents a beautiful appearance, 
the metallic fibres being thickly interspersed amongst the untrans¬ 
muted ones, or traversing the black carbonaceous ground like gold 
threads on velvet. Portions of the siliceous cores are often pyritous, 
and in one or two specimens the siliceous granules are replaced 
by pyritous granules, although isolated dark siliceous spots or veins 
and thin films of jet occur in the granular base of pyrites and carbon. 
The successive steps of the transforming process as exhibited in 
these and Colonel Butterworth’s specimen bear a striking resem¬ 
blance to the gradations which are sometimes seen in the silicifying 
process which the sedimentary rocks of the southern portion of the 
Peninsula (as well as the northern) have in many places under¬ 
gone. Just as we see the thin layers and films of lignite preserved 
in the completely petrified base, so in the cliffs of Cape Rachado- 
we see minute films of the original micaceous clayey rock occuring 
in the heart of the quartz into which it has been converted. Nu¬ 
merous analogous instances everywhere present themselves, and af¬ 
ford the clearest indications of the gradual and often gentle action* 
* Such it must have been in the case of the partial conversion of the Li- 
goi jet into a siliceous and pyritous rock, because a violent and powerful ac- 
