Most here think it's a BBW because it looks like a BBW despite it not being the same color as your other BBW and gives purple slurry. BBWs are so common that the chance of a stone like that being something else is very small. If you show us a close-up of the stone without slurry this time I expect to see a BBW pattern.

I think 70 strokes on the stone was just fine for a test, most natural stones are slow on water. Without having any magnification you can also compare how polished/shiny the bevel is before and after honing.

With the stone being most likely coarser than your Guangxi I doubt the stone can be a Fox or a Vosgienne.

Btw what size it?