What is the longevity of slate chippings?

The only experience I have of these is finding them in a client's garden and knowing they will (unfortunately) last decades - but that's on beds and borders as a hard mulch, not used on a path., although, at times it was necessary to walk over the slate, I can say its quite slippy and moves about a fair bit, especially in wet weather.There must be a risk of breaking and cracking, as you say, but perhaps someone else has used them for the same purpose and can give a better answer. I'd choose gravel and insert stepping stone slabs along the run of the path for ease of walking; its fairly ubiquitous as a solution, but I guess you could use the slate round the slabs instead to make it a little different.

I think Karen had a brilliant idea with using flagstone to line the path and gravel as a filler between the stones. Whether you use pea gravel or slate chips as a filler is entirely to your preference. The flagstone is stable and much more pleasant to walk upon especially if you do barefoot gardening.

Here is Karen's blog if you'd like to see what she's done.

http://www.growsonyou.com/cottagekaren/blog/31843-back-garden-finished

Thanks both for the tips - the slipperiness/movement is something I hadn't considered and I can see how that would make a difference.

I don't think I will be using flagstone 'island' stepping stones, I just don't think it will suit the look of the garden. But, for the most part, I don't have to walk down the path when gardening so, barefoot or not, it shouldn't be a problem.

Nobody wants to walk on gravel barefoot, never mind slate chips. Good luck.