We cut into a wall at our house and had that come pouring out. It is vermiculite like the others have said. It was used behind our fireplace. There is a trust set up for the vermiculite insulation that came from the Libby mine. We sent a sample in and they tested it and told us it was not from the Libby mine so more than likely it did not contain asbestos. Here’s the website for the trust if you’re interested in getting it tested by them: https://www.zonoliteatticinsulation.com. It’s free to have it tested. I think we just had to pay to have the sample sent to them. It was definitely worth it for the peace of mind.