I don’t think the livestock and slaves appreciate that very much.
Space Magic is always the right answer.
It should be hard to imagine compressing any of it, as solids don’t really compress much unless subjected to at least planetary-core levels of pressure, and even then they won’t compress much. So, compressing ore is silly, and especially compressing it to a point that the whole ore ends up much smaller than the small amount of stuff you take out of it.
completely depends on what state the ore is in when mined. Is it a fine sand? large oddly shaped rocks? massive bolders?