You need gunzip this file and gunziped file blockchain.bin move to .aeon
Are you under linux-64?
Yes that I did. No success.
Yes Mint 17, 64 , I work now from my backup 140 day old.
in the OP, the file extension is .gz but it should have been .tgz (or .tar.gz).
when you extract (with gunzip) "aeon_bootstrap_5_5_2015_linux_x64.gz" you obtain the file named "aeon_bootstrap_5_5_2015_linux_x64"
but this file "aeon_bootstrap_5_5_2015_linux_x64" is a tar archive without .tar extension. it's confusing.
to obtain correct blockchain.bin file, you must rename "aeon_bootstrap_5_5_2015_linux_x64" in "aeon_bootstrap_5_5_2015_linux_x64.tar" in graphic mode or in cli:
mv aeon_bootstrap_5_5_2015_linux_x64 aeon_bootstrap_5_5_2015_linux_x64.tar
then you can extract "blockchain.bin" as usual or in cli:
tar -xvf aeon_bootstrap_5_5_2015_linux_x64.tar
@Phantas: could you check your archive format (the one in the OP), i think the .gz extension must be corrected with .tgz