Aurumack (also sometimes called Auromack) is a valueable stone that makes up most of the rocks on some remote islands. It is an extremely sturdy stone, having much of the strength of steel, though more prone to fracturing because it is much more brittle. It is also very lightweight, almost enough to allow it to float on water (though it just sinks slowly).
Most islands which contain aurumack have buildings constructed from the stone due to both its ease of use and its availability. The stone is formed from naturally-occuring clays found buried in the island's underwater areas. These clays can be fired to produce more auromack, with mineral additives used during the firing process to alter the appearance of the resulting stone.
Analysis by mages have shown that these clays are infused with a mixture of both Air and Stone Nitor, which give it the properties of lightness and strength respectively. Attempts to reproduce Aurumack have met with mixed success, though no methods are able to produce Aurumack more cheaply than by harvesting natural deposits of it.
Sky Elves and some dragons frequently make use of Aurumack to construct floating sky islands.