PERMINERALIZATION
Permineralization is the technical term for the
fossilization style seen in “petrified wood”. “Petrified” is a horrible
term to a paleontologist. Biogenic materials such as wood or bone have a
fair amount of small-scale porosity. After burial, the porosity of wood
or bone can get filled up with minerals as groundwater or diagenetic fluids
percolate through. The end result is a harder, denser material that
retains the original three-dimensionality (or close to it). The wood or
bone has become “petrified”. Well, no - it’s become permineralized.
Not surprisingly, the most common permineralization mineral is quartz (SiO2).
Sometimes, fossil wood and bone have been permineralized with radioactive
minerals such as uraninite (UO2) or carnotite (K2(UO2)2(VO4)2·3H2O). Recently, fossil bones permineralized with cinnabar
have been identified (García-Alix et al., 2013, Lethaia 46: 1-6).
Permineralized wood - large, beautiful cut-and-polished slice of
petrified wood (24.6 cm across), permineralized with quartz. Note that
the original concentric tree ring structure is still apparent. Unrecorded
stratigraphy & locality, but likely from the Upper Triassic of Arizona.
Permineralized wood (left: 3.6 cm across; right: 3.3 cm
across) - small pieces of petrified wood having preserved bark & tree ring
structure. Provenance: attributed to the Mesozoic of Madagascar.
Dinosaur bone partially permineralized with the yellowish, radioactive mineral carnotite
(K2(UO2)2(VO4)2·3H2O).
Possibly derived from the Morrison Formation (Jurassic) of Colorado, USA.
(Colorado School of Mines Geology Museum, Golden, Colorado, USA)