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| Titel |
A radiological study of some ornamental stones: the bluish granites from Extremadura (Spain) |
| VerfasserIn |
D. Pereira, L. Neves, A. Pereira, M. Peinado, J. A. Blanco, J. J. Tejado |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 2 ; Nr. 12, no. 2 (2012-02-17), S.395-401 |
| Datensatznummer |
250010508
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| Publikation (Nr.) |
 copernicus.org/nhess-12-395-2012.pdf |
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| Zusammenfassung |
| In the area of Trujillo (Extremadura, Spain) we have found a variety of
striking bluish and secondary yellow granites outcropping within the
Plasenzuela pluton. They are all quarried under different names and are
characterized by leucocratic minerals in which a bluish phosphate is
dispersed throughout the rock. Their physical and mechanical properties make
these granites a perfect option for most applications as ornamental rocks.
Within the pluton the radiological background is fairly homogeneous, with no
significant differences between the gamma ray fluxes of the different
facies. U (6.4 ± 0.51 ppm), Th (2.9 ± 0.47 ppm) and K2O (4.32 ± 0.26%)
contents determined in the laboratory by gamma-ray spectrometry
from representative samples are in good accordance with fast in situ measurements
carried out with the same technique and also with conventional chemical
analysis. Estimated activities for K-40, Ra-226 and Th-232 were, on average,
1022 ± 36 Bq kg−1, 84 ± 9 Bq kg−1 and 6.8 ± 1.6 Bq kg−1.
On the basis of these results, the I index of EU technical
document 112 was determined, with an average result of 0.66 ± 0.03. This
suggests that the rock can be used with no restrictions for all types of
construction purposes. Striking differences were observed between the blue
facies and the yellow facies in radon exhalation tests from crushed material
(0.03 Bq kg−1 vs. 0.20 Bq kg−1). Since both granites have similar
uranium contents (6.3 ppm and 6.5 ppm, respectively), these results can
probably be explained in terms of important differences in the mineralogical
distribution of this chemical element, radon emanation being enhanced in the
yellow facies. However, due to the ordinary use as ornamental stone, the
yellow facies does not present a radiological risk in terms of excess
effective dose due to internal exposure to radon. |
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