Are there any other Canadians here on this forum? What potting mix do you use? I've heard lots of good things about pumice but it seems like no one carries horticultural pumice here.

Yesterday I was walking around in a Canadian tire (it's an automotive/home improvement/sports and outdoors store) and somehow this bag of black stuff caught my attention.

Here are some relevant quotes from the back of the bag:

"The youngest and most easterly eruptive center in the Anahim belt produced a deep carpet of black pumice (lapillo), a natural lightweight aggregate. Black pumice is a volcanic glass of low density and high surface porosity (60%). It's naturally jagged and uneven surface allows LavaGrip to imbed itself in snow and ice offering instant traction."

"...100% natural and chemically inert with a neutral pH of 6.8. This makes end of season disposal safe and efficient as users can sweep any excess into gardens or lawns with no negative effects to the surrounding soil and vegetation."

So according to that, it's pumice with no additives, pH neutral and harmless to plants. It also came from a major, accessible store chain with locations across the nation.

What do you think? Does it look like usable pumice for potting amaryllis and other things? Here's a picture of the grains.