Obsidian sources of the Coromandel Volcanic Zone, Northern New Zealand

The Coromandel Volcanic Zone includes nine geographically discrete obsidian sources (Fanal, Awana, Te Ahumata, Cooks Beach, Hahei, Tairua, Whangamata, Maratoto and Waihi). Each has a distinctive chemical composition, and some can also be differentiated on the basis of visual characteristics of the obsidian. Chemically, the three northern sources (Fanal, Awana, Te Ahumata), constituting the 'Great Barrier Group', are distinguished by high Rb concentrations and a high Rb/Sr ratio. Obsidian from six of the sources is known to have been utilized by pre-European Maori for the manufacture of flake tools, but at present there is no evidence for exploitation of the Awana, Maratoto and Tairua deposits.