grub-install /dev/sdc
grub-probe: error: failed to get canonical path of `/cow'.
Installing for i386-pc platform.
grub-install.real: error: failed to get canonical path of `/cow'.

mint ~ # sudo grub-install --root-directory=/mnt/ /dev/sdc
grub-probe: error: failed to get canonical path of `/cow'.
Installing for i386-pc platform.
grub-install.real: warning: this GPT partition label contains no BIOS Boot Partition; embedding won't be possible.
grub-install.real: warning: Embedding is not possible.  GRUB can only be installed in this setup by using blocklists.  However, blocklists are UNRELIABLE and their use is discouraged..
grub-install.real: error: will not proceed with blocklists.