File:Luminescent hyalite opal (Sierra Madre Occidental Volcanic Province, mid-Tertiary; Zacatecas, Mexico) 9 (35778426181).jpg
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[edit]DescriptionLuminescent hyalite opal (Sierra Madre Occidental Volcanic Province, mid-Tertiary; Zacatecas, Mexico) 9 (35778426181).jpg |
Faceted hyalite opal from the Tertiary of Mexico. (public display, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA) The greenish-glowing gemstone shown above is cut & faceted hyalite opal (SiO2·nH2O - hydrous silica). Hyalite is also known as glass opal. It is composed of opal-AN, which refers to amorphous opal having a network structure similar to silica glass, rather than opal consisting of silica gel spheres/colloids (most opal is the latter type). Hyalite is normally clear/colorless. Under incandescent lighting, this Mexican material is clear to extremely pale yellow. The greenish coloration is a type of luminescence - fluorescence. Under ultraviolet light (UV light; black light) and in direct sunlight and in indirect sunlight and in blue laser pointer light, this hyalite glows greenish. Published research has shown that the greenish luminescence is from ultraviolet excitation of uranyl impurities in the hyalite opal (Fritsch et al., 2015a, 2015b). Uranyl is a UO2 +2 ion - uranium dioxide with a double positive electric charge. This Mexican hyalite is indeed slightly radioactive, but the radiation levels do not pose a health risk (Fritsch et al., 2015b). Several uranium-bearing minerals have been identified in the opal's host rocks, including meta-autunite, haiweeite, uranophane, meta-uranospinite, and others (Fritsch et al., 2015a). The gemstone is derived from luminescent botryoidal hyalite opal occurring on devitrified rhyolitic volcanic tuff matrix. This new opal variety, discovered in 2013, has been nicknamed "electric opal". Geologic context & age: Sierra Madre Occidental Volcanic Province, mid-Tertiary Locality: undisclosed site on a high mesa in Zacatecas State, central Mexico Info. mostly synthesized from: Fritsch et al. (2015a) - Green-luminescing, gem hyalite opal from Zacatecas, Mexico. 34th International Gemmological Conference, August 2015, Vilnius, Lithuania: 101-104. Fritsch et al. (2015b) - Green-luminescing hyalite opal from Zacatecas, Mexico. Journal of Gemmology 34: 490-508. |
Date | |
Source | Luminescent hyalite opal (Sierra Madre Occidental Volcanic Province, mid-Tertiary; Zacatecas, Mexico) 9 |
Author | James St. John |
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/35778426181 (archive). It was reviewed on 30 November 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
30 November 2019
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current | 16:54, 30 November 2019 | 1,358 × 946 (525 KB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via #flickr2commons |
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Camera manufacturer | Canon |
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Camera model | Canon PowerShot D10 |
Exposure time | 1/60 sec (0.016666666666667) |
F-number | f/13 |
ISO speed rating | 80 |
Date and time of data generation | 13:02, 12 July 2017 |
Lens focal length | 14.303 mm |
Image title | |
Width | 4,000 px |
Height | 3,000 px |
Bits per component |
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Pixel composition | RGB |
Orientation | Normal |
Number of components | 3 |
Horizontal resolution | 180 dpi |
Vertical resolution | 180 dpi |
Software used | Adobe Photoshop Elements 13.0 (Macintosh) |
File change date and time | 22:50, 13 July 2017 |
Y and C positioning | Co-sited |
Exif version | 2.21 |
Date and time of digitizing | 13:02, 12 July 2017 |
Meaning of each component |
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APEX shutter speed | 5.90625 |
APEX aperture | 7.40625 |
APEX exposure bias | −1 |
Maximum land aperture | 4.34375 APEX (f/4.51) |
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Flash | Flash fired, compulsory flash firing, red-eye reduction mode |
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Focal plane resolution unit | inches |
Sensing method | One-chip color area sensor |
File source | Digital still camera |
Custom image processing | Normal process |
Exposure mode | Manual exposure |
White balance | Auto white balance |
Digital zoom ratio | 1 |
Scene capture type | Portrait |
Lens used | 6.2-18.6 mm |
Date metadata was last modified | 18:50, 13 July 2017 |
Unique ID of original document | 18E64D153C93451B323272EB7EA3A347 |