I've saved a log from a chipper. The heartwood is just at the right stage of rotten. I've suffered multiple cuts and had 3 splinters punch up right underneath my fingernails. I've ended up with this: The only way I can describe it, is clay. But how can it be clay? It's timber heartwood many metres from the ground. It had some termites in it, but theoretically it's 100% organic matter. It's entirely moist, and feels like it would never dry out. Very fine, very dense, sticky (which is why it reminds me of clay). At the moment, I'm considering maybe a 5% addition to a potting mix recipe. It seems that dense, any more would cause anaerobic conditions in the mix. Any other ideas?