Well Wailele, I'm not sure how that works with fossils.
Petrified wood has completely altered to silica. Agates are also mostly silica, so you could say the pet wood is "agatized". But, even tho I use that word, "agatized", occasionally, I'm not really sure it's a real word.
Some dino bone will alter to silica, like wood, but it is not common and is very sought after material. That large bone was "fossilized" but not "agatized". What the chemistry is of different stages of "fossilization" is way above my pay grade,
, but would be interesting to read about.
The "agatized" dino bone was the main thing I went to the auction looking for. Unfortunately, this one other lady with much deeper pockets than mine was looking for the same thing and she ended up with the best pieces. Below are a couple pics of the agatized bone I did get. I hope you can see how the bone has now altered to shiny silica and beautiful colors like pet wood, and not like some old bone. The close-up pic is so you can see the cellular structure still preserved in the bone. It's really beautiful, rare, material.
And of course you know what the big blob of agate sitting behind the bone in pic 1 is? Yep, coprolite. Dino doo doo. Pies from the sky.
He had, literally, over a ton of some of the nicest doo doo I've ever seen. Some with dog-tooth calcite crystal lined vugs and some with the prettiest purple chalcedony ever. I went for the purple and didn't end up with much of the calcite.