Curtis, Neville J., Gascooke, Jason R., Johnston, Martin R., Pring, Allan (2019) A Review of the Classification of Opal with Reference to Recent New Localities. Minerals, 9 (5) 299 doi:10.3390/min9050299
| Reference Type | Journal (article/letter/editorial) | ||
|---|---|---|---|
| Title | A Review of the Classification of Opal with Reference to Recent New Localities | ||
| Journal | Minerals | ||
| Authors | Curtis, Neville J. | Author | |
| Gascooke, Jason R. | Author | ||
| Johnston, Martin R. | Author | ||
| Pring, Allan | Author | ||
| Year | 2019 (May 15) | Volume | < 9 |
| Page(s) | 299 | Issue | < 5 > |
| Publisher | MDPI AG | ||
| URL | |||
| DOI | doi:10.3390/min9050299Search in ResearchGate | ||
| Original Entry | Curtis, N.J., Gascooke, J.R., Johnston, M.R., Pring, A. (2019) A review of the classification of opal with reference to recent new localities. Minerals: 9(5): 299. [https://doi.org/10.3390/min9050299] | ||
| Classification | Not set | LoC | Not set |
| Mindat Ref. ID | 16119014 | Long-form Identifier | mindat:1:5:16119014:9 |
| GUID | 2ec1e5f2-9419-470b-9c3e-efe0baea7788 | ||
| Full Reference | Curtis, Neville J., Gascooke, Jason R., Johnston, Martin R., Pring, Allan (2019) A Review of the Classification of Opal with Reference to Recent New Localities. Minerals, 9 (5) 299 doi:10.3390/min9050299 | ||
| Plain Text | Curtis, Neville J., Gascooke, Jason R., Johnston, Martin R., Pring, Allan (2019) A Review of the Classification of Opal with Reference to Recent New Localities. Minerals, 9 (5) 299 doi:10.3390/min9050299 | ||
| In | Link this record to the correct parent record (if possible) | ||
| Abstract/Notes | Our examination of over 230 worldwide opal samples shows that X-ray diffraction (XRD) remains the best primary method for delineation and classification of opal-A, opal-CT and opal-C, though we found that mid-range infra-red spectroscopy provides an acceptable alternative. Raman, infra-red and nuclear magnetic resonance spectroscopy may also provide additional information to assist in classification and provenance. The corpus of results indicated that the opal-CT group covers a range of structural states and will benefit from further multi-technique analysis. At the one end are the opal-CTs that provide a simple XRD pattern (“simple” opal-CT) that includes Ethiopian play-of-colour samples, which are not opal-A. At the other end of the range are those opal-CTs that give a complex XRD pattern (“complex” opal-CT). The majority of opal-CT samples fall at this end of the range, though some show play-of-colour. Raman spectra provide some correlation. Specimens from new opal finds were examined. Those from Ethiopia, Kazakhstan, Madagascar, Peru, Tanzania and Turkey all proved to be opal-CT. Of the three specimens examined from Indonesian localities, one proved to be opal-A, while a second sample and the play-of-colour opal from West Java was a “simple” Opal-CT. Evidence for two transitional types having characteristics of opal-A and opal-CT, and “simple” opal-CT and opal-C are presented. | ||
References Listed
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| Not Yet Imported: Journal of Research of the National Bureau of Standards - journal-article : 10.6028/jres.061.009 If you would like this item imported into the Digital Library, please contact us quoting Journal ID 46751 | |
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Mineral Pages
| Mineral | Citation Details |
|---|---|
| Opal | |
| Opal-A |
See Also
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