The ludwigite in Fengcheng of Liaoning Province belongs to low-iron and low-boron low-grade mixed ore.

• 辽宁凤城地区的硼镁铁矿属低铁低硼的贫杂矿；三氧化二硼质量分数仅7.；90%25；三氧化二铁质量分数仅30