Iron sand from Piha beach in New Zealand
It what happens if you touch the sand with a magnet - you get an "iron brush" (fun for kids)!
Famous for surfing, Piha beach is made up of that black "iron sand"
In fact it is titano-magnetite sand.
It had previously been thought that the black iron sand of Piha arrived from the eruption
of Mt Taranaki, but recent study shows that the sand supply of the West Coast is titano-magnetite sand primarily from the eruption of Taupo (Oruanui eruption), brought our way by the Waikato River.
The Taupo volcano is one of the world's largest known eruption It occurred around 26,500 years ago.
Taupo is 300km south from that Piha peach.
See my photo of Piha below (and on the map - geotagged)