Sunset Jasper is found on Hamersley Station, a large cattle grazing property about 75 km west of Tom Price in the Pilbara region of Western Australia.
Sunset Jasper is a metamorphosed sedimentary rock that is part of the quartz family, being very high in silica but with a high percentage of impurities, in this case mainly iron oxides. These iron impurities give Sunset Jasper its mixed range of colours, from vivid reds through to various shades of yellow, cream, brown, and grey. The stone often has vughs of higher purity iron in the form of goethite pisolites. Interestingly, the deposit has 3 distinct layers, each with its own palette of colours and patterns.
The deposit sits adjacent to the Marra Mamba iron formation, in one of Western Australia’s main iron ore provinces, which explains its high iron content. It is close to operating iron ore mines. This area was once a vast inland sea, where iron was pumped from underground vents into a very calm body of water. The heavy iron particles settled in layers on the sea floor, building up over time. Heat, pressure and an oxygen atmosphere, transformed these layers into the iron ore we see today. The Sunset Jasper was a later but similar layered formation, with much of the iron replaced by silica. The iron formations date back 2.4 – 2.8 billion years, but the jasper deposit is likely younger than this.
With a MOH’s hardness of 6 – 6.5, Sunset Jasper is well suited to beads and cabochons, specimen pieces and slabs, carvings and other ornamental objects.