The Machine Block is a crucial component in most Industrial Craft recipes. It is made out of 8 Refined Iron. It can also be placed like a normal block, if desired.
The majority of machines in Industrial Craft will revert back to this block if mined with a pickaxe. Therefore, it is better to right click the machines with a Wrench or an Electric Wrench.
Advanced Machine Block
TGP Tekkit - Episode 4 - Industrial Craft (Getting Started)(09:31)