Roughly one metre cubes, two deep red oblong stones lie in a semi-circle collection of stones. A fragment of the wavering thickness of living/non-living layering of the earth's crust, of what Elizabeth Povinelli has described as geontology (Povinelli 2016), they form part of the Australian National Rock Collection near Galambary or Black Mountain, Canberra (see Figure IV.1). The stones have the width, depth and breadth, surfaces, extremities and angles that reflect their formation and their handling in the mining industry. In the Pilbara, the rock was cut out of the ground by Fortescue Metals Group, one of the world's largest iron ore mining companies. Saved from crushing and shipping as iron ore at the mine, they are now climbed by children and present a training challenge for passing mountain bikers.

The boulders come from the Brockman Formation of the Hamersley Ranges in the mineral-rich Pilbara region of north-west Australia, Pitjanjare country. The 2.3-billion-year-old rocks were cut from a geological formation of vast horizontal stability, millions of square kilometres of central and western Australia, that geologists call ‘a platform’. Much of Australia's landmass and large parts of Eurasia are platforms. The rock is banded with waves of iron compounds taken up by marine microbes and sedimented in fine oxide layers. Continental platforms are usually made up of layers of sedimentary rock washed by water across the much older basalt or other igneous ‘basement’ of Precambrian eons.

Hammersley iron is a platform deposit (Morris 1983).