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obsidian

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Journal Article
Published: 01 November 2023
American Mineralogist (2023) 108 (11): 2105–2120.
...David London Abstract Drilled cores of Macusani green obsidian pebbles from Peru were hydrated and melted above their liquidus temperatures at 200 MPa to a single column ~4 cm in length and then undercooled in a thermal gradient >150 °C along the length of the cores. Despite thousands of hours...
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Journal Article
Journal: Geosphere
Published: 18 January 2023
Geosphere (2023) 19 (2): 431–448.
... often regarded as acting independently throughout an eruptive event. In this study, we documented evidence of a continuum of brittle and brittle-ductile deformation and fracture-induced outgassing during the emplacement of the ~600-yr-old silicic lava from Obsidian Dome, California, USA. This study...
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Journal Article
Journal: Elements
Published: 01 August 2022
Elements (2022) 18 (4): 246–250.
.... Indigenous peoples have many oral histories directly attributable to geological processes, such as earthquakes, landslides, and volcanic eruptions, and the subduction zone also provides critical technological and economic resources, including obsidian, important metals such as gold and mercury, and road...
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Series: EMU Notes in Mineralogy series
Published: 01 January 2019
DOI: 10.1180/EMU-notes.20.8
EISBN: 9780903056625
..., the range of gemstones is quite narrow. However, a number of unusual gemstones are found in Japan, including sugilite, a relatively rare pink to purple silicate mineral. One gemstone common to volcanic areas is obsidian. Indeed, there are >80 archaeological obsidian sources in Japan. In addition...
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Series: EMU Notes in Mineralogy series
Published: 01 January 2019
DOI: 10.1180/EMU-notes.20.11
EISBN: 9780903056625
... Obsidian is a volcanic product that forms under particular geological conditions, and hence occurs in limited areas of the Earth. In ancient times, obsidian was used successfully by various peoples to produce artistic artefacts, but also to make tools and weapons used in everyday life...
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Journal Article
Journal: Geology
Published: 05 October 2017
Geology (2017) 45 (11): 1019–1022.
... composition of dacite and not rhyolite. 21 02 2017 07 08 2017 08 08 2017 © 2017 Geological Society of America 2017 Previously published petrologic and experimental studies on GM obsidians allow a test of this hypothesis. Sparse, euhedral sanidines in GM obsidians span...
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Journal Article
Published: 01 August 2017
American Mineralogist (2017) 102 (8): 1677–1689.
... by Daniel Neuville FTIR water H 2 O speciation volcanic glass rhyolite andesite hydration obsidian The dissolved water content of a silicate melt affects a range of magmatic processes, since it exerts a strong influence on melt viscosity (e.g., Hess and Dingwell 1996 ; Giordano et...
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Journal Article
Published: 01 June 2017
Italian Journal of Geosciences (2017) 136 (2): 238–262.
... as caementia . The grey-black volcanic rocks are glasses with characteristics more near to obsidian and less to natural pozzolan normally used in the Roman period. To identify the provenance of these glasses, a geochemical comparison between the samples taken from the theatre mortars and the volcanic outcrops...
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Journal Article
Journal: Geology
Published: 01 February 2017
Geology (2017) 45 (2): 183–186.
... fragments. We show that individual obsidian pyroclasts from Mono Craters, California (USA), are heterogeneous in dissolved H 2 O and CO 2 , suggesting that clasts are assembled from juvenile melt and rewelded ash during magma ascent. This is in contrast to the conventional view that clasts are chemically...
Journal Article
Journal: Geology
Published: 01 July 2015
Geology (2015) 43 (7): 647–650.
...Kenneth S. Befus; James Watkins; James E. Gardner; Dominique Richard; Kevin M. Befus; Nathan R. Miller; Donald B. Dingwell Abstract Spherulites in rhyolitic obsidian provide a record of the thermal history of their host lava during the interval of spherulite growth. We use trace element...
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Journal Article
Published: 01 June 2015
European Journal of Mineralogy (2015) 27 (3): 353–363.
..., minor and trace elements. Two main groups of natron-based silica–lime glass were identified, as well as one sample of obsidian (from Lipari Island). The majority of the samples (20) are High Iron, Manganese and Titanium (HIMT) glass. Specifically, most of them (18) can be classified as HIMT1, with only...
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Journal Article
Published: 01 April 2015
American Mineralogist (2015) 100 (4): 774–786.
...Amy G. Ryan; James K. Russell; Alexander R.L. Nichols; Kai-Uwe Hess; Lucy A. Porritt Abstract We present a suite of 36 high-temperature (900–1100 °C) experiments performed on 10 × 10 mm unjacketed cores of rhyolitic obsidian from Hrafntinnuhryggur, Krafla, Iceland, under atmospheric pressure...
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Journal Article
Published: 01 July 2014
American Mineralogist (2014) 99 (7): 1383–1403.
... material of common granitic composition (Lake County obsidian) reduces the crystallization and melting temperatures by approximately 50–70 and 200 °C, respectively, and promotes the formation of quartz-feldspar graphic and granophyric intergrowths. The presence of Li in the hydrous granitic system lowers...
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Journal Article
Published: 01 May 2014
American Mineralogist (2014) 99 (5-6): 1085–1094.
.... Powders from two natural obsidian samples were also studied and yielded results broadly similar to the synthetic model systems. SO 2 adsorption on ash is partially irreversible; it appears that the first layer of SO 2 molecules absorbed on the surface cannot be removed. The pressure and temperature...
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Journal Article
Published: 01 October 2013
The Canadian Mineralogist (2013) 51 (5): 705–714.
... the additional degree of freedom for a melt. Formation of snowflake obsidian is discussed in view of our synthesis experiments. § Corresponding author : Hofmeist@wustl.edu ; 314-935-7440; fax 935-7361 31 07 2013 06 11 2013 © The Mineralogical Association of Canada 2013 laser-flash...
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Journal Article
Journal: Geology
Published: 01 July 2013
Geology (2013) 41 (7): 779–782.
...Kurt Rademaker; Michael D. Glascock; Bruce Kaiser; David Gibson; Daniel R. Lux; Martin G. Yates Abstract We report results from comprehensive mapping and multi-technique geochemical characterization of obsidian from the Alca source in the Peruvian Andes (15.3°S, 72.7°W), aimed at understanding...
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Journal Article
Journal: Clay Minerals
Published: 01 June 2013
Clay Minerals (2013) 48 (3): 423–445.
...J. Cuadros; B. Afsin; P. Jadubansa; M. Ardakani; C. Ascaso; J. Wierzchos Abstract Rhyolitic obsidian was reacted with natural waters to study the effect of water chemistry and biological activity on the composition and formation mechanisms of clay. Two sets of experiments (18 months, 6 years) used...
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Journal Article
Journal: Geology
Published: 01 January 2013
Geology (2013) 41 (1): 7–10.
... crystallization ages for two obsidian-bearing lavas: Red Island (the host for the granophyre) and Obsidian Butte, a prehistoric quarry for obsidian that is widely distributed in southern California and northern Mexico archaeological sites. Lavas and granophyre display overlapping zircon crystallization age...
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Journal Article
Journal: Geology
Published: 01 August 2012
Geology (2012) 40 (8): 699–702.
...James M. Watkins; Michael Manga; Donald J. DePaolo Abstract Water concentration profiles around bubbles offer a new kind of geobarometer. We measure H 2 O and CO 2 concentrations in glass adjacent to bubbles in pyroclastic obsidian from Mono Craters, California (United States). H 2 O and CO 2...
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Journal Article
Journal: Geology
Published: 01 January 2011
Geology (2011) 39 (1): 67–70.
...Agustín Cabrera; Roberto F. Weinberg; Heather M.N. Wright; Sergio Zlotnik; Ray A.F. Cas Abstract We present water content transects across a healed fault in pyroclastic obsidian from Lami pumice cone, Lipari, Italy, using synchrotron Fourier transform infrared spectroscopy. Results indicate...
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