In The North’s Economic Development Plan, I noticed you didn’t mention the northern mountains. Do you think there’s nothing worthwhile to mine in them?

Just an oversight. There might be useful minerals, there might not be, and it’s not clear in what quantities. 

But the main thing is, I don’t think the North is going to have an absolute or comparative advantage there compared to other regions, so it would run the risk of having its products out-competed in price by the Westerlands or somewhere else and losing money. And as long as it’s part of the Westerosi monarchy, it can’t protect its mining and metalworking industries with tariffs or import quotas.

Especially in the early stages, the North doesn’t have a large population or much capital to burn, so it needs to concentrate its efforts in areas where it’s most likely to succeed. Down the road, it might have the money and manpower to invest in mining and manufacturing in the Northern mountains, but mining and manufacturing aren’t super-cheap industries to invest in.