Mining criticals on mining missions

How do mining criticals interact with mining missions? Say I’m doing a level 4 mining mission mining the allegory for gniess ore. I get a critical mine. Do I just get extra of the worthless mission ore, or will it be totally awesome and exciting and I get actual gniess.

Another example say I’m mining the geodite which is an allegory for crokite. Will I get crokite on the critical mine, or just useless extra crokite. And how mining missions function, if it’s just useless mission ore, it’s actually going to be a negative to get a critical unless they code it correctly.

I really would love the added excitement of getting occasional awesome mining criticals on mining missions if they do the awesome thing and let you get the actual ore on mining criticals instead of extra useless mission ore. The mining criticals would also maybe cause you to make an extra trip but if it’s for a hard to get ore that makes it awesome.

Why is getting mission ore a negative?

You’d be done faster with the mission!

Or am I misunderstanding how mining missions work? (I never do missions.)

But if it causes any problems like residue CCP might disable crits for mission ores, I guess? I’m sure there are solutions.