Spalting, It's Beautiful!
Spalting is any form of wood coloration caused by fungi. Although primarily found in dead trees, spalting can also occur in living trees under stress. The unique coloration and patterns of spalted wood are sought by woodworkers. Wikipedia
Indeed, spalted wood is certainly sought after by me! It can be really difficult to work with though because spalting can cause soft spots in the wood. To overcome the soft spots I use very thin CA glue (super glue). After turning the piece to rough dimension, i apply the glue with a foam brush and let it soak in. It dries almost instantly. The glue stiffens the fibers in the wood. I take the glue off of the surface with a gouge or scraper on the lathe and then sand like usual.
Spalting can produce many colors. I’ve seen purple, green, orange, brown, red and very often the patches are surrounded by ink black transition lines.