Discussion of the Results 
Macroscopically, the resulting lithomorphs closely resemble 
a number of natural petrifactions of geologically young age. 
Comparable specimens include (1) a monocotyledonous wood 
(Cordyline sp.) of Recent age (mineralized with silica as a 
consequence of burial in volcanic ash from an eruption in 1886 
of Mt. Tarawera in New Zealand, (2) a silicified coniferous 
wood from Wyoming, radiocarbon dated at less than 3000 
years b.p., and (3) a silicified dicotyledonous wood of Miocene 
age from Colorado. The freshly formed silica of the synthetic 
lithomorphs, although brittle, is ordinarily sufficiently cohe- 
rent and continuous to permit removal of all organic matter 
without damage in form or structure of the lithomorph. It is 
highly permeable and will imbibe water readily, becoming less 
opaque and more translucent in doing so. Compositionally, it is 
a silica gel with appreciable water content; crystallographi- 
cally, it is essentially amorphous. Its x-ray diffraction pattern 
(highly disordered alpha cristobalite) is like that observed by 
Jones et al. (1964) for most natural opals (opal-C), such as the 
common ‘potch’ associated with precious opals. The 
aforementioned less than century old natural petrifaction from 
New Zealand was x-rayed also and the pattern obtained was 
identical to that obtained from the synthetic lithomorphs. 
Although the lithomorphs generally are not of sufficient 
strength and induration to permit preparation of transverse thin 
sections for microscopy purposes by conventional techniques 
or without first embedding, macerations of longitudinal sec- 
tions can be easily prepared by simply teasing apart the silice- 
ous tissue replica with a dissecting needle. Scanning electron 
micrographs and white light photomicrographs of sections pre- 
pared in this manner appear in Plates | through 4. The trans- 
verse sectional views appearing in the scanning electron mic- 
rographs in Plates 5 and 6 were prepared by fracture of the 
specimen to expose a fresh cross-sectional surface and then 
mounting the specimen upright on an aluminum stub. It is 
apparent from these micrographs that even the detail of such 
delicate cellular features as the bordered pits in conifer 
tracheids and scalariform perforation plates in angiosperm 
vessel elements has been faithfully replicated in silica. These 
micrographs of silica replicated features in the synthetic 
lithomorphs are essentially indistinguishable from those pre- 
15 
