hought these mining opreations were very rare buildings and the technology would just be a boost for them.
@reyori I wished that these card mines BTC or ETH but it doesn't. 
@gerber named these cards so to distinguish the percentage of SIM income boost by tier. Similar to sports Gold medal for 1st place , Silver for 2nd and Bronze (HIVE) for 3rd.
RE: Double Mining-BTC Discovery?!!