I know a little bit of a house built of iron ore, but it only just in the acient times, or in remote rural areas. This is mainly due to the fact that the connection between rock blocks is not strong enough to resist natural disasters. So in modern China, most of the houses are brick-concrete structures.

I think it is a recycling of scraps of iron. In this type of walls bonding between iron and mortar will be weak, and also heavy weight and corrosion are disadvantages.

Best regards

Not aware of any cases here. I have worked on restoration of a 200 year old building where the stone had a high iron content, which meant that it 'rusted' - the faces of some of the stone blocks spalled and fell off, exposing the core and requiring replacement

Regards

In Poland, it isn't recycled from scraps of iron. It is typical bog ore located shallow under the ground level. It was used in the historical buildings which were located in poor areas - there were no stones or little clay to construct. The wood was to value to build a whole building on a farm, so the iron bog ore was used on barns or other outhouses.