What is "ironsand"

Ironsand also known as iron-sand and iron sand is a type of sand with heavy concentrations of iron. It is typically dark grey or blackish in colour.

It comprises mainly magnetite, FeO, and also contains small amounts of titanium, silica, manganese, calcium and vanadium.

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 like Piha.