A Review of the mineralogical opal classification

Neville Curtis and colleagues discuss an update from their investigations and experimental data for the mineralogical aspects of Opal-A (Opal-AG, Opal-AN), Opal-CT and Opal-C by X-ray Diffraction, Infrared Spectroscopy, Raman Spectroscopy and NMR (Nuclear Magnetic Resonance. The group analysed over 230 opal samples from world wide sources.


Anthony Smallwood