The group mark will be U+2BD2. For details see https://github.com/shirriff/groupmark

You can find it here where it says it's in Stage 6 which I would imagine why it's not in the current chart: http://unicode.org/alloc/Pipeline.html

2BD2 GROUP MARK 2015-May-05 Accepted 2016-May-29 Stage 6

The bitcoin symbol is in there too.