Why Swedish iron ore was strategically valuable

What made Swedish iron ore special, and did other countries have comparable deposits?

Its exceptional purity made consistent high-quality alloys easier to produce, although the United States, Britain, and other countries also possessed useful deposits.

Cleaner ore requires less work to remove impurities before it can be turned into controlled, high-quality alloys. That processing advantage made Swedish deposits unusually attractive even though they were not the world's only source of good iron ore. The exchange helps connect raw-material quality to armor, guns, machinery, and shipbuilding capacity.