Unknown acoustic material

Hi, While I'm still shopping for rockwool, I found this new stuff (at least to me). I don't know what it is, but it is far cheaper. And the vendor here usually only provide goods and don't know what they're for, so the vendor can't give any info regarding the quality and even the name of the material, they only know that it's for soundproofing. That's it. It's an acoustic material, made from mixture of shredded wood and cement. Does anybody know what it is? And is it good? If it's good, I probably will substitute it for the rockwool. What do you guys think? Ari

I think I know of the stuff - it's used in drop ceilings sometimes. I don't think it would subsitute for rockwool. cheers john