Composition: Various minerals replacing wood and preserving its structure
Nomenclature: The term "petrified wood" is somewhat of a misnomer since it incorrectly implies that the wood has somehow "turned" into stone. Technically, this material is described as a pseudomorph after wood, since the mineral replaces the wood, preserving the wood's structure but not the wood itself.
Industrial Uses: Ornamental stone, jewelry.
Additional Notes: Petrified wood is a class of objects defined by the process by which it was created rather than by chemical composition. Many different minerals may replace wood over the course of geologic time. Most discovered petrified wood is quartz, in the form of agate or opal.
Afars & Issas : Scott C101 : 85 francs : 25 Oct 1974
Gypsum (Petrified Wood)
Ecuador : Scott 1444 : 2000 sucre : 6 Oct 1997
Petrified wood
Kenya : Scott 103 : 70 cents : 13 Dec 1977
Agate (quartz; petrified wood)
United States : Scott 1538 : 10 cents : 13 Jun 1974
Agate (quartz; petrified wood)