Xylopal

Xylopal was a form of petrified wood with a more lustrous beauty.

Description
Xylopal was similar to tempskya (petrified wood) except the wood fiber was replaced by opal instead of quartz. Sometimes called opalized wood or lithoxyle, it was highly prized for its beauty (it made good bookends). Especially detailed pieces could be used as inlays or for jewelry. A typical price was 22sp per pound (0.45kg).