Wood is not a mineral. A mineral is a naturally occurring inorganic solid with a definite chemical composition and an ordered internal structure. Although wood is a naturally occurring solid, it is an organic material, so it is not a mineral.
Although wood is not considered a mineral, petrified wood is. Petrified wood is formed when wood is submersed in water containing one or more minerals for a very long time. The minerals eventually fill up the pores of the wood and replace all of the organic material. The resulting copy is considered a mineral, as no organic material is left.