Ironsand, also known as iron-sand or iron sand, is a type of sand with heavy concentrations of iron. It is typically dark grey or blackish in color.
It is composed mainly of magnetite, Fe3O4, and also contains small amounts of titanium, silica, manganese, calcium and vanadium.[1]
Ironsand has a tendency to heat up in direct sunlight, causing temperatures high enough to cause minor burns. As such it forms a hazard in New Zealand at popular west-coast surf beaches such as Piha.[2]
The beach is made up of black iron sand which can become overly hot during the summer and walking in the water or with shoes on will protect your feet from burning.