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Obsidian

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Colour:black, bluish, mahogany, ...


Volcanic glass - a rock rather than a mineral, it is a mixture of cryptocrystalline grains of silica minerals in a glass-like suspension, a super-cooled liquid. Obsidian is formed in the latest stage of volcanic eruptions, the silicas left over after most of the other elements and water have been used up are ejected or flow out and rapidly chilled at surface temperatures.

Note on "Transparent/Translucent Obsidian":
A lot of gem-quality water-clear variously coloured 'obsidian' has been offered for sale on the internet (in particular on auction websites) with a variety of sources listed. The material offered for sale is in fact an artificial glass mass-produced in places such as Indonesia.

Visit gemdat.org for gemological information about Obsidian. Currently in public beta-test.

Classification of Obsidian

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Physical Properties of Obsidian

Lustre:Vitreous
Diaphaneity (Transparency):Translucent
Colour:black, bluish, mahogany, golden, peacock, etc. - the colors due largely to refraction by microscopic bubbles (and microscopic mineral inclusions such as magnetit in "Rainbow Obsidian").
Fracture:Conchoidal

Other Names for Obsidian

Synonyms:
BergmahoganyBlack Lava GlassŒqinolitŒqinoliteVolcanic Glass
Xaga
Other Languages:
Simplified Chinese:火山玻璃
Spanish:Œqinolita
Varieties:
Apache TearsFire ObsidianMahogany ObsidianRainbow ObsidianSheen Obsidian
Snowflake Obsidian

Other Information

Health Warning:Obsidian is a natural glass and may have razor-sharp edges that can easily cut skin and flesh. Handle with care. Do not grind dry since long-term exposure to finely ground powder may lead to silicosis.

References for Obsidian

Reference List:

- +
Stevenson, R.J., Dingwell, D.B., Webb,S.L., and Bagdassarov, N.S. (1995) The equivalence of enthalpy and shear stress relaxation in rhyolitic obsidians and quantification of the liquid-glass transition in volcanic processes. Journal Volcan. Geotherm. Res.: 68: 297-306.

F. Eder, C. Neelmeijer, N. Pearce, M. Bichler, J.H. Sterba, T. Ntaflos, S. Merchel (2013): Volcanic glass under fire - a comparison of three complementary analytical methods. X-Ray Spectrometry, 42, 412-422.

http://members.peak.org/~obsidian/index.html (International Association for Obsidian Studies)

Mindat.org articles about Obsidian

Blog entries:
"Family of Rockhounds"Ann-Marie Jay

Internet Links for Obsidian

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  • Localities for Obsidian

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Antarctica
     
    • Eastern Antarctica
      • Victoria Land
        • Malta Plateau
    Ganovex III expedition
    Argentina
     
    • Catamarca
      • Antofagasta de la Sierra Department
    R. N. Alonso (1999). Los salares de la Puna y sus recursos evaporíticos, Jujuy, Salta y Catamarca. En: Recursos Minerales de la República Argentina (Ed. E.O. Zappettini), Instituto de Geología y Recursos Minerales. SEGEMAR, Anales 35: 1907-1921.
    Raúl Jorge Tauber Larry
    • Salta
    Raúl Jorge Tauber Larry
    Raúl Jorge Tauber Larry;
      • Los Andes Department
    Alonso, R. N., de los Hoyos, L., González Barry, C. E. (2004). Minería, propuestas y reflexiones sobre una actividad productiva esencial. Cámara Minera de Jujuy, Centro de Geólogos de Jujuy.
    Alonso, R. N., de los Hoyos, L., González Barry, C. E. (2004). Minería, propuestas y reflexiones sobre una actividad productiva esencial. Cámara Minera de Jujuy, Centro de Geólogos de Jujuy.
    Secretaria de Minería, Industria y Recursos Energéticos de la provincia
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    http://www.unsa.edu.ar/ibigeo/images/PDFs/N3/Obsidiana.pdf
    Alonso, R. N., de los Hoyos, L., González Barry, C. E. (2004). Minería, propuestas y reflexiones sobre una actividad productiva esencial. Cámara Minera de Jujuy, Centro de Geólogos de Jujuy.
    Armenia
     
    • Kotayk' Province
    http://geo.web.ru/druza/page-47.html
    Australia
     
    • Victoria
      • City of Greater Geelong
        • Anakie
          • Mount Anakie
    Birch et al. (2008) Australian Journal of Mineralogy, 14(1), 37-42.
    Bolivia
     
    • Potosí Department
    Alfredo Petrov collection
    Canada
     
    • British Columbia
      • Kamloops Mining Division
    Richard Gunter Collection
    China
     
    • Jiangsu Province
      • Huai'an Prefecture
        • Xuyi Co.
    Tianhu Chen, Xiaochun Xu, Shucang Yue, and Jinzhong Li (2002): Geology and Prospecting 38(2), 49-54
    Ethiopia
     
    • Oromia Province (Oromiya Province)
    Alfredo Petrov field observations, 1972.
    • Sidamo-Borana Province
      • Awassa
    Macdonald, R., and Gibson, I.L. (1969): Contributions to Mineralogy and Petrology 24, 239-244.
    Georgia
     
    • Samtskhe-Javakheti Region
    Alexander G. Tvalchrelidze, Georges Morizot (2003) Mineral Resource Base of the Southern Caucasus and Systems for its Management in the XXIst Century. Springer 204pp
    Greece
     
    • Aegean Islands Department (Aiyaíon)
      • Kykládes Prefecture
        • Cyclade Islands (Cyclades; Kikladhes; Nomos Kikladhon)
    Martins da Pedra collection
    • South Aegean Department
      • Dodekánisos Prefecture (Dodekánissa)
        • Dodecanese Islands
    L. Rantos collection
    Lefteris Rantos
    Hungary
     
    • Borsod-Abaúj-Zemplén Co.
      • Zemplén Mtns (Tokaj Mtns)
    Koch: Minerals of Hungary,1986
    Iceland
     
    • Northeastern Region
      • Myvatn
    Found by Frank de Wit
    Italy
     
    • Sicily
      • Messina Province
        • Eolie Islands (Aeolian Islands)
          • Lipari
            • Lipari Island
    Antonio Borrelli and Tamás Ungvári collections
    • Trentino-Alto Adige
      • Trento Province
        • Ala
          • Pilcante
    "Giorgio Bortolozzi (visual identification)"
    • Tuscany
      • Siena Province
        • Murlo
    C. Betti, G. Pagani (2000): Minerali del Senese. Cento località mineralogiche nella provincia di Siena. - Protagon Ed. Toscani, Siena
    Japan
     
    • Hokkaido
      • Hidaka Province
        • Monbetsu (Mombetsu)
    Masutomi Museum specimens (Kyoto)
    • Tokyo Prefecture
      • Volcano Islands (Kazan Rettou)
    Wakimizu, T. (1908). The ephemeral volcanic island in the Iwojima group.
    Gordon A. MacDonald (1948) Petrography of Iwo Jima. Bulletin of the GSA, 59, 1009-1018.
    Gordon A. MacDonald (1948) Petrography of Iwo Jima. Bulletin of the GSA, 59, 1009-1018.
    Madagascar
     
    • Antsiranana Province
      • Diana Region (Northern Region)
        • Ambanja District
          • Ampasindava Peninsula
            • Betaimboay
              • Unnamed caldera
    Wolfgang Hampel, site visit May 2012
    Mexico
     
    Smith, 1949. Gemstones, 10th ed. revised
    • Jalisco
      • Mun. de Magdalena
        • San Andreas
    Information verbal from Alfredo Banos owner of the mine
    Smith, 1949. Gemstones, 10th ed. revised
    New Zealand
     
    • North Island
      • Waikato
        • Taupo
    Rod Martin personal collection
    Giorgio Bortolozzi
    Peru
     
    J.Hyrsl (2012) Gemstones of Peru, p. 55
    J.Hyrsl (2012) Gemstones of Peru, p. 55
    • Junín Department
      • Yauli Province
    Hewett, D. F. (1910) Vanadium Deposits in Peru. Transactions of the American Institute of Mining, Metallurgical Engineering 40:274-299
    Poland
     
    • Lower Silesia (Dolnośląskie)
      • Kłodzko District
        • Lądek Zdrój commune
    Personally collected by Zając Piotr in 2012
    Portugal
     
    • Azores District
      • Terceira Island
        • Angra do Heroísmo
    Martins da Pedra collection
    Slovakia
     
    • Košice Region
      • Trebišov Co.
    Kaličiak, M., Ďuďa, R., 1996: Geolgický vývoj, stavba a metalogenéza neovulkanitov na Východnom Slovensku. Manuskript, Archív Geofond, Bratislava, 83p
    Turkey
    Rui Nunes collection
    • Eastern Anatolia Region
      • Bitlis Province
    Rui Nunes collection
    USA
     
    • Arizona
      • Coconino Co.
        • Coconino National Forest
    Phillips, K.A. (1987), Arizona Industrial Minerals, AZ Dept. of Mines & Mineral Resources Rpt. 4.
    Mitchell, 2001. Gem Trails of Arizona, p.56.
        • San Franciscan volcanic field (San Francisco Peaks; San Francisco Mts)
          • O'Leary Peak
    Robinson, Henry H. (1913), The San Franciscan volcanic field, AZ, USGS PP 76: 65.
          • Sitgreaves Peak (Sitgreaves Mt.)
    Robinson, Henry H. (1913), The San Franciscan volcanic field, AZ, USGS PP 76: 67.
    Robinson, Henry H. (1913), The San Franciscan volcanic field, AZ, USGS PP 76: 67.
    Robinson, Henry H. (1913), The San Franciscan volcanic field, AZ, USGS PP 76: 67.
      • Graham Co.
        • Black Hills
    MRDS database Dep. ID #10024056.
      • Greenlee Co.
        • Shannon Mts
          • Copper Mountain District (Clifton-Morenci District)
            • Clifton
    Bearce, 2006. Minerals, Fossils and Fluorescents of Arizona
      • Pinal Co.
        • Pinal Mts
          • Pioneer District
    P Cristofono collection
    MRDS database Dep. ID #10064155, MRDS ID #TC38415.
        • Superior District
          • Superior
            • Picketpost Mountain area
    MRDS database Dep. ID #10064153, MRDS ID #TC38413.
    MRDS database Dep. ID #10060368.
      • Yuma Co.
        • Tank Mts
          • Tank Mountains District
    Shackley, M.S. (1991) Tank Mountains obsidian - A newly discovered archaeological obsidian source in east-central Yuma County, Arizona: Kiva: 57(1): 17-25.
    • California
      • Imperial Co.
        • Niland
    Rogers, Austin Flint (1935), Salton volcanic domes of Imperial County, California (abstract): Geological Society of America, Proceedings, 1934: 328; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 181; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 457; CFMS Newsletter, January 2003.
        • Plaster City
        • Salton Sea
    Rogers, Austin Flint (1925), Geology of Cormorant Island, Salton Sea, Imperial County, California, …(abstract): Geological Society of America Bulletin: 37: 219; Rogers, Austin Flint (1928), Natural history of the silica minerals: American Mineralogist: 13: 219; Rogers, Austin Flint (1935), Salton volcanic domes of Imperial County, California (abstract): Geological Society of America, Proceedings, 1934: 328; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 162, 372; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 351.
      • Inyo Co.
        • Coso Mts (Coso Range)
          • Coso District (New Coso District)
            • Sugarloaf Mountain
    Rogers, Austin Flint (1922), A new occurrence of cristobalite in California: Journal of Geology: 30: 211-216; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 162.
    Rutley, Frank (1890), On composite spherulites in obsidian from Hot Springs, near Little Lake, California: Geological Society of London Quarterly Journal: 46: 423-428; Rogers, Austin Flint (1922), A new occurrence of cristobalite in California: Journal of Geology: 30: 213-215; Bowen, N.L. (1935), Ferrosilite as a natural mineral: American Journal of Science, 5th. Series: 30: 481; Bradley, W.W. (1940), Thirty-sixth report of the State Mineralogist: California Division Mines Report 36: 107; Pemberton, H. Earl (1983), Minerals of California: 351, 386, 457.
    Bowen, N.L. (1935), Ferrosilite as a natural mineral: American Journal of Science, 5th. Series: 30: 481 (491 ?); Bradley, W.W. (1940), Thirty-sixth report of the State Mineralogist: California Division Mines Report 36: 107; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 307.
      • Lake Co.
        • Sulphur Creek District (Sulfur Creek District; Wilbur Springs District)
          • Clear Lake Oaks
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
      • Modoc Co.
        • Warner Mts
          • Davis Creek
    www.vgms.org/bt/vgms0004.htm (The Ventura Gem & Mineral Society, Inc. (VGMS)).
    Industrial West Foundation, Non-Metallics II-D: 71; USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10115839.
          • Sugar Hill
    Gems & Minerals (1966): April: 23.
    [var: Mahogany Obsidian] P Cristofono collection
    Bailey, R. A. (1989) Geologic map of the Long Valley caldera, Mono-Inyo Craters volcanic chain, and vicinity, eastern California. USGS IMAP 1933
    Haas, P. (1992), site visit.
    USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10031513.
    Loney, R.A. (1968) Flow structure and composition of the Southern Coulee, Mono Craters, California – a pumaceous rhyolite flow. Geological Society of America Memorandum 116: 423, 428; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 354, 361.
      • Napa Co.
        • Mayacmas Mts (Mayacamas Mts)
          • Calistoga District (Silverado District)
            • St. Helena
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
      • Siskiyou Co.
        • Cascade Range
          • Cougar Butte
    Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 163; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 354.
    Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 181; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 459.
    • Colorado
      • Chaffee Co.
        • Nathrop
    USGS Bull 1716C
      • Hinsdale Co.
        • Galena District (Henson Creek District)
    Minerals of Colorado (1997) E.B. Eckels
    • Hawaii
      • Hawaii Co. (Hawaii Island)
        • Hualalai Volcano
    www.hawaiinews.com/archives/volcano_watch/000309.shtml
    (Specimens in innumerable collections, often as the wind-spun filiform variety known as "Pele's hair".)
    • Idaho
      • Blaine Co.
        • Snake River Area
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    • Nevada
      • Esmeralda Co.
    NBMG Spec Pub 31 Minerals of Nevada
    NBMG Spec Pub 31 Minerals of Nevada
        • Montezuma District
    NBMG Spec Pub 31 Minerals of Nevada
      • Lander Co.
        • Wild Horse District
    NBMG Bull 80 Geology and Mineral Deposits of Lander County, Nevada
      • Nye Co.
    NBMG Spec Pub 31 Minerals of Nevada
      • Washoe Co.
    NBMG Spec Pub 31 Minerals of Nevada
    • New Mexico
    www.swxrflab.net/mulecr.htm
      • Cibola Co.
    James M. Barker, Virginia T. McLemore, Marc L. Wilson, and George S. Austin, (1989) East Grants ridge--A mineral potpourri. in 40th Field Conference New Mexico Geological Society, pp. 325-329.
      • Doña Ana Co.
    Minerals of New Mexico 3rd ed.
    NMBMMR Bull 11 The Geology of the Organ Mountains
    www.swxrflab.net/mulecr.htm
      • Luna Co.
        • Little Florida Mountains District
    http://geoinfo.nmt.edu/tour/stateparks/rockhound/home.htm
      • San Juan Co.
    Minerals of New Mexico 3rd ed.
      • Sandoval Co.
    [var: Mahogany Obsidian] www.cst.cmich.edu/users/dietr1rv/obsidian.htm
        • Valle Grande
    Minerals of New Mexico 3rd ed.
    • Oregon
      • Deschutes Co.
        • East Lake
    The ORE BIN Volume 31, No.4 April 1969 pp 73-87; Mineralogy of 10 Geothermal boreholes drilled in and around the Newberry Caldera U.S. Geological Survey Professional Paper, Issue 1578 By Keith E. Bargar, Terry E. C. Keith 1999
      • Lake Co.
    The Canadian Mineralogist Vol. 45, pp. 551-557 (2007)
    • Utah
      • Beaver Co.
        • Milford
    Rick Dalrymple
      • Box Elder Co.
        • Promontory Mts
          • Promontory District
    UGMS Bull 117 Minerals and Mineral Localities of Utah
      • Iron Co.
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
      • Juab Co.
        • Dugway Pass area
    Rick Dalrymple Collection
    UGMS Bull 117 Minerals and Mineral Localities of Utah
      • Millard Co.
        • Antelope Springs (Wheeler Amphitheater)
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
        • Black Rock Desert
    UGMS Bull 117 Minerals and Mineral Localities of Utah
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    UGMS Bull 117 Minerals and Mineral Localities of Utah
      • Piute Co.
    UGMS Bull 117 Minerals and Mineral Localities of Utah
    • Wyoming
      • Park Co.
        • Yellowstone National Park
    www.obsidianlab.com/universe.html
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    Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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