So I installed Go, Mercurial and GMP and then tried to install ethereum through the prompt.
"go get -u -t github.com/ethereum/go-ethereum"
in file included from src/github.com/obscuren/secp256k1-go/secp256.go:9:
In file included from ././secp256k1/src/secp256k1.c:5:
In file included from ././secp256k1/src/impl/num.h:8:
In file included from ././secp256k1/src/impl/../num.h:9:
././secp256k1/src/num_gmp.h:8:10: fatal error: 'gmp.h' file not found
1 error generated.
So their is sth. missing in obscurens repository, I guess.