Would amsteel blue rope be appropriate for use in anchor building for climbing or mountaineering? I expect it's not very abrasion resistant so it wouldn't be good up against some rock or an edge. But could it be used in something like a T-slot or as a runner in space?
Amsteel blue is a dyneema cord that size-for-size is just as strong as steel cable. It'll hold. In terms of abrasion resistance, dyneema happens to be superior to nylon rope when it comes to wear and tear.
There are two factors to consider when using dyneema: It has a lower melting point than nylon (which means it's more prone to breaking when knots are tied in it); and, it doesn't hold knots as well. You're going to have to learn new knots to tie that will hold in dyneema cord.
It would work well enough as a throw away rap anchor if you can learn how to tie it, but I wouldn't suggest investing in it specifically for climbing.