Mammoth Tusk Repair - Advice Needed

[GPayton]

This is my second mammoth tusk of the year, but while the first I found was rock solid and all that remained was one side of the tusk, this one is whole and a lot more fragile. After getting it home I made the stupid decision to wash it off in the sink, thinking that the sandstone matrix adhering to the tusk was just ordinary sand and river gravel and would come off just as easily. Instead, the water soaked into the tusk's core and when I tried picking it up it snapped in half.  

It took a couple of days sitting under a window and wrapped in paper towels for the water to finally get drawn back out, but the damage was clearly already done. The outer surface of the tusk is pretty thoroughly mineralized, but the inside is incredibly crumbly. 

I've seen several posts on the forum already about using butvar solution to stabilize mammoth tusks, but I couldn't find anything that gave a clear, step-by-step guide that would be easy enough for a newbie like me to follow. Aside from stabilizing the tusk, I'd also obviously need to glue the two broken halves back together where they broke apart. However, that's complicated by the fact that tiny pieces of the ivory fell off in the area around the crack when it broke. If you look close in the pictures, you can see that the two halves don't meet up perfectly in the middle anymore. Is there some sort of epoxy or something I could use to fill in that gap? 

The side of the tusk with the sandstone accretions: 

The side of the tusk without the sandstone accretions: 

[GPayton]

Inside view of the larger half of the tusk after breaking: 

Inside view of the "tip" of the tusk after breaking:

[snolly50]

Here is a recent thread that may be of value. Good luck, have fun.