I don't know about "opalized" - actually, I need to look that term up. What makes the piece interesting (to me) is how the wood silicified with one side being nearly 100% of one growth ring. That's pretty cool!
I agree with IAMZIM, opal tends to have a glassy appearance. But, if you want to know for certain; a hardness test will settle that.
Quartz will scratch Opal, but not chalcedony which I believe this one to be made of.