Yes, it is mineable.  It is PoS, proof of stake. So the mining is called "staking".  I am new on PoS, still learning. The closest to this coin is blackcoin because the wallet says it cloned blackcoin source code.

For total supply is tough to know the whole picture.  A while ago I saw in my wallet total money supply is 5 billion, recently I saw 12 billion. Not fully sure the total supply there on SLFI.  

Another that I found on PoS staking. This wallet staking takes 100% CPU load.  It does take a lot of CPU power if your wallet has lots of small chunks and addresses holding SLFI on stake mining.