Ochre is a natural clay earth pigment which is a mixture of ferric oxide and varying amounts of clay and sand. Ochre ranges in colour from white through yellow to orange, brown and red.
The quarry at the listed coordinates was mined for thousands of years by the local Aboriginal people. Ochre quarried here was judged to be such high quality that it was traded with other groups of Aborigines who lived hundreds and even thousands of kilometres away.
These quarries were of great importance to the aborigines as they provided a rich source of multi–coloured variations of ochre used for ceremonial purposes. This quarry was the focus of well defined trade routes extending north into the Northern Territory, Queensland and south to the coast. No European mechanical mining has occurred in this quarry.
Ochre has been used for millennia by Aboriginal Australians for body decoration, sun protection, mortuary practices, cave painting, bark painting and other artwork, the preservation of animal skins, among other uses.
- White clay contains no contamination.
- Yellow ochre contains FeO(OH)·nH2O (limonite)a hydrated iron hydroxide.
- Brown ochre contains FeO(OH) (goethite) a partly hydrated iron oxide.
- Red ochre contains Fe2O3 (hematite) an anhydrous iron oxide.
- Purple ochre, is identical to red ochre chemically but of a different hue caused by different light diffraction properties associated with a greater average particle size.
- Sienna pigments contains both limonite and a small amount of manganese oxide, which makes it a darker colour than yellow ochre.
- Umber pigments contain a larger proportion of manganese, which makes a darker brown.
Earthcache Tasks. Please send your answers to the cache owner.
- What colours do you see at this earthcache.
- Are the variations in colours discrete or blended? Why is this so?