 | | Journal (article/letter/editorial) | | minerals Article A Review of the Classification of Opal with Reference to Recent New Localities Neville...Abstract: Our examination of over 230 worldwide opal samples shows that X-ray diffraction (XRD) remains...for delineation and classification of opal-A, opal-CT and opal-C, though we found that mid-range infra-red...provenance. The corpus of results indicated that the opal-CT group covers a range of structural states and...At the one end are the opal-CTs that provide a simple XRD pattern (“simple” opal-CT) that includes Ethiopian |
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Voznesenovka, Martuk District, Aktobe Region, Kazakhstan