My mistake. The stuff i bought was Fossilized as you mention, not Carbonized.
Made a decent shooting bow and seemed to be quiet. Just heavier mass weight than it needs to be for the application
I've already given you these numbers by phone, but for the sake of sharing info, this new stuff weighs 1104 grains for a 35 7/8" 1.75x .090 par lam, the same exact lam using the fossilized material is 1526 grains.
The difference in the deflection strength is 5/8" on the fossilized, and 1" on the carbonized material. So the fossilized stuff is considerably stronger..... But If you compare 5/8 vs 8/8 in deflection & 1104 vs 1526 in weight you are looking at pretty close to the same strength per weight ratio, but .....the heavier material is much thinner now to get the same strength, and your stack height lower.... So i wouldn't write this heavier mass weight material off at all.
There are other properties to consider using the Fossilized material to take into account too. This material doesn't take a set like carbonized bamboo does. It has a much higher janka rating, and much higher compression qualities. It also gives a lighter draw weight recurve more torsional stability too. I've built a quite a few bows now using the fossilized material and its held up well. but i believe it does better in lighter draw weight recurves than heavier draw weights for performance vs carbonized bamboo.
The deflection tests is .090 thick material at 10" using a 3 ounce weight.
Food for thought..... Kirk