This small sandstone seed-grinding stone is from near Bourke in western New South Wales.  The grinding stone was made by pecking and is moderately worn on one face.   The stone is from the traditional country of the Ngemba people, and is probably less than 2000 years old.

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This small artefact is a bottom stone used in seed grinding.  The grinding stone is made from relatively coarse sandstone.  One face is unused and is stained by iron oxides from the bedrock bedding planes.  The opposite face is moderately worn by attrition, creating a concave surface.  The slab appears to have been shaped by pecking with a hammerstone  rather than direct percussion flaking, but the coarse material mostly obscures discrete pit-marks.

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Grinding stones like this were critical tools for subsisting in the arid zone of Australia during the Holocene period.  Aboriginal people used them to grind native grass seeds into flour.  Grinding stones were often made at quarries associated with sacred storylines, and the stones were extensively traded throughout the arid zone.

Quarries for grinding stones are present in the Gunderbooka Range near Bourke in outback New South Wales, 75-100 km east and southeast of where this grinding stone was found.  Extensive sandstone quarries are present on Oombi Oombi (Mount Oxley) and Yambacoona (Mount Druid), both of which are sacred sites on storylines.  Archaeologists recorded 370 quarry pits at Yambacoona.  Here Aboriginal people wedged sandstone slabs from bedrock to produce blanks measuring about 10-50 cm in maximum dimension, with most around 20 cm long.  Charles Sturt explored the region in 1828 and mistook the quarry pits on Oombi Oombi as natural phenomena, created by ‘eddies of water’, despite his observation that the sandstone slabs ‘. . . were as clean as if they had only just been turned out of the hand of the mason’.