I'm a little skeptical of soluble minerals. General wisdom for chinchillas is to avoid them.
I have used a different tunnel and it was really nice when it lasted, I think I had it for about a year before it got grungy. It was made by SuperPet and they call it fiddlesticks (Google "super pet fiddlesticks" and you'll see many examples) but I think there are other versions of it out there. It is basically wood pieces wired together. I bent it into a tunnel and put it on the floor of the cage. If you find and order one make sure to get the large because the small is for hamsters and small rodents.
