After few weeks trying on marble deposits my geologist with "lucky find" skill, I did find extra marble deposits. 3 times actually in 2 different spots in sector 9 and sector 4. So skill works on marble deposits without many issues. I still am unlucky finding extra iron deposit.
So I was wondering what differs my marble deposits from iron deposits. There were 2 factors. 1st was the arctic mine with 8k iron ore, so I depleted it and let it collapse. 2nd is me having 4 more iron deposits on additional small islands. I have no way to abandon those small island sectors. The mechanic of the game is not allowing demolishing the last storage in sector.
I think this is bug. Serious bug, which was introduced with new island map updated with the small islands. So why devs can't fix it on my island?
It is like 4th month I am sending my geologist with "lucky find" skill and not discovering any extra iron deposit at all.