346 
REsiNiTE xYLoiDE of Hauy. In these the characters of wood are 
so distinctly marked, that no one can entertain the least doubt of 
their having originated from wood. The resinous, or waxy lustre, 
which they manifest, has been already examined, as to the degree 
of evidence it affords of the wood having existed in a bituminous 
state. Their fracture, perhaps, serves also to further prove their 
ligneous origin ; since although this is in general conchoidal, it will 
frequently, when longitudinal, be splintery, and even fibrous, in the 
direction of the fibres of wood. Their colours vary very much 
from milk white, through all the shades of brown and yellow, to 
green, red, and black ; but their most frequent colours are those, 
which approach so near to that of the original wood, blended with 
that of common resin, as to corroborate strongly the idea of the 
wood having been softened down, into a resiniform substance, 
previous to its impregnation with silex. Their transparency, which 
is sometimes such as to admit light through them freely, and even, 
when in thin slices, such as to allow objects to be seen through 
them, is a circumstance which it is impossible to account for in 
any other way so well as by supposing the wood to have been ren- 
dered a clear bitumen during its first change. A specimen of this 
kind of pitch-stone, or fossil wood, possessing in its internal part a 
considerable degree of transparency, whilst the external part bears 
the appearance of recent wood, is figured in Plate III. Fig. 8. 
These fossil woods are also characterized by a circumstance which 
has excited the admiration of mineralogists, and which at the same 
time seems to manifest the intermixture of some substance with the 
.silex which does not seem to exist in any other stone of the silicious 
genus — although they appear, from their peculiar kind of lustre, to 
be little harder than resin, and sometimes give fire with steel with 
difilculty, they yet are more difficult to be scratched than many that 
do this more freely. 
The combination of bitumen and silex, in these specimens of 
