Natural Yellow Oxide - Our yellow oxide is a single pigment color made of natural hydrated iron oxide mineral from India. Hydrated iron oxide is the principle coloring agent in yellow oxides. This color is based on the natural mineral goethite associated with varying proportions of others mineral such as clay, chalk, and silica. They differ from red ochers in that they contain water. In other words, the iron to which they owe their color is hydrated iron oxide. Natural yellow oxides are opaque, absolutely permanent and have good covering power. They are typically more opaque than yellow ochers, because they contain a greater amount of iron oxide.