Abstract
A fairly large (ca. 15 cm), massive glassy specimen of nearly black bulk colour, found in Ratnapura district, was identified as metamict gadolinite–(Y) based on its chemical composition Y1.4Ln0.6Ca0.1Fe0.9Be2Si2O10 (with Ln = lanthanide elements La–Lu) and since the material reconstituted to monoclinic gadolinite–(Y) after two days of dry annealing in air at 1150 °C. Thin slabs (< 0.5 mm) of the specimen are bottle-green and transparent. Apart from surface weathering and small inclusions, the material is fairly homogeneous and does not show any indication of chemical alteration. Concentrations of Th (6310 ppm) and U (3360 ppm) in the material, and its calculated time-integrated alpha dose of ca. 8.5 × 1018 g–1 based on the 206Pb/238U age of ca. 518 Ma, explain the present glassy state as being caused by radioactive self-irradiation over geological periods of time.
Originalsprache | Englisch |
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Seiten (von - bis) | 23-30 |
Seitenumfang | 8 |
Fachzeitschrift | Journal of the Geological Society of Sri Lanka |
Jahrgang | 24 |
Ausgabenummer | 1 |
Publikationsstatus | Veröffentlicht - 11 Okt. 2023 |
ÖFOS 2012
- 104026 Spektroskopie
- 105116 Mineralogie
- 105113 Kristallographie