musée

Type de contenu

496 image(s) · 24 Actualités

Galerie d'images

Blue Dinosaur Royal Ontario Museum
Taxons Argentinosauria

Blue Dinosaur Royal Ontario Museum

musée États-Unis Argentinosauria Argentinosauridae +3
Museum of Zoology of the University of São Paulo, Brazil
Taxons Tapuiasaurus

Museum of Zoology of the University of São Paulo, Brazil

musée Brésil Tapuiasaurus
Fossil of Mosasaurus, an extinct mosasaur, reconstruction of the Mosasaurus of Bemelen. Took the photo at Natural History Museum of Maastricht

Fossil of Mosasaurus, an extinct mosasaur, reconstruction of the Mosasaurus of Bemelen. Took the photo at Natural History Museum of Maastricht

musée fossile Moanasaurus Mosasaurus
Henan Geological Museum, Zhengzhou, China. Complete indexed photo collection at WorldHistoryPics.com.
Taxons Placoolithus

Henan Geological Museum, Zhengzhou, China. Complete indexed photo collection at WorldHistoryPics.com.

musée Chine Placoolithus
Herbivorous dinosaur found in the Al-khoudh area.  This dinosaur is similar to the Zalmoxes and Rhabdodon dinosaurs.  The skeleton in the Bait Al Baranda Museum was assembled from bones borrowed from several museums.

Herbivorous dinosaur found in the Al-khoudh area. This dinosaur is similar to the Zalmoxes and Rhabdodon dinosaurs. The skeleton in the Bait Al Baranda Museum was assembled from bones borrowed from several museums.

os musée Dinosauria Mochlodon +3
Banded fine-grained pyrite in shale from the Precambrian of Australia. (public display, Leadville Mining Museum, Leadville, Colorado, USA)
A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties.  At its simplest, a mineral is a naturally-occurring solid chemical.  Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common.  Mineral classification is based on anion chemistry.  Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.
The sulfide minerals contain one or more sulfide anions (S-2).  The sulfides are usually considered together with the arsenide minerals, the sulfarsenide minerals, and the telluride minerals.  Many sulfides are economically significant, as they occur commonly in ores.  The metals that combine with S-2 are mainly Fe, Cu, Ni, Ag, etc.  Most sulfides have a metallic luster, are moderately soft, and are noticeably heavy for their size.  These minerals will not form in the presence of free oxygen.  Under an oxygen-rich atmosphere, sulfide minerals tend to chemically weather to various oxide and hydroxide minerals.
Pyrite is a common iron sulfide mineral (FeS2).  It’s nickname is “fool's gold”.  Pyrite has a metallic luster, brassy gold color (in contrast to the deep rich yellow gold color of true gold - www.flickr.com/photos/jsjgeology/sets/72157651325153769/), dark gray to black streak, is hard (H=6 to 6.5), has no cleavage, and is moderately heavy for its size.  It often forms cubic crystals or pyritohedrons (crystals having pentagonal faces).
Pyrite is common in many hydrothermal veins, shales, coals, various metamorphic rocks, and massive sulfide deposits.
The rock shown above consists of numerous bands of fine-grained pyrite interbedded with dark shale.  Published research has shown that the pyrite is diagenetic, formed by sulfate reduction from sulfate-bearing groundwater that moved along bedding planes of the Urquhart Shale host rocks (see Painter et al., 1999).  The sulfate source was evaporitic gypsum-anhydrite-barite in the same stratigraphic unit.
Stratigraphy: Urquhart Shale, Mount Isa Group, Mesoproterozoic, ~1655 Ma
Age of metamorphism: peak greenschist-facies metamorphism at ~1505 Ma during the Isan Orogeny
Locality: Mount Isa Mines, northwestern Queensland, northeastern Australia


Some info. from:
Kawasaki & Symons (2010) - Dating of Mesoproterozoic metamorphism in the Mount Isa and George Fisher Zn-Pb-Cu-Ag deposits, Australia, by paleomagnetism.  American Geophysical Union, Fall Meeting 2010, Abstract GP33C-0953.
Painter et al. (1999) - Sedimentologic, petrographic, and sulfur isotope constraints on fine-grained pyrite formation at Mount Isa Mine and environs, northwest Queensland, Australia.  Economic Geology 94: 883-912.


Photo gallery of pyrite:

www.mindat.org/gallery.php?min=3314
Intervalles Mesoproterozoic

Banded fine-grained pyrite in shale from the Precambrian of Australia. (public display, Leadville Mining Museum, Leadville, Colorado, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The sulfide minerals contain one or more sulfide anions (S-2). The sulfides are usually considered together with the arsenide minerals, the sulfarsenide minerals, and the telluride minerals. Many sulfides are economically significant, as they occur commonly in ores. The metals that combine with S-2 are mainly Fe, Cu, Ni, Ag, etc. Most sulfides have a metallic luster, are moderately soft, and are noticeably heavy for their size. These minerals will not form in the presence of free oxygen. Under an oxygen-rich atmosphere, sulfide minerals tend to chemically weather to various oxide and hydroxide minerals. Pyrite is a common iron sulfide mineral (FeS2). It’s nickname is “fool's gold”. Pyrite has a metallic luster, brassy gold color (in contrast to the deep rich yellow gold color of true gold - www.flickr.com/photos/jsjgeology/sets/72157651325153769/), dark gray to black streak, is hard (H=6 to 6.5), has no cleavage, and is moderately heavy for its size. It often forms cubic crystals or pyritohedrons (crystals having pentagonal faces). Pyrite is common in many hydrothermal veins, shales, coals, various metamorphic rocks, and massive sulfide deposits. The rock shown above consists of numerous bands of fine-grained pyrite interbedded with dark shale. Published research has shown that the pyrite is diagenetic, formed by sulfate reduction from sulfate-bearing groundwater that moved along bedding planes of the Urquhart Shale host rocks (see Painter et al., 1999). The sulfate source was evaporitic gypsum-anhydrite-barite in the same stratigraphic unit. Stratigraphy: Urquhart Shale, Mount Isa Group, Mesoproterozoic, ~1655 Ma Age of metamorphism: peak greenschist-facies metamorphism at ~1505 Ma during the Isan Orogeny Locality: Mount Isa Mines, northwestern Queensland, northeastern Australia Some info. from: Kawasaki & Symons (2010) - Dating of Mesoproterozoic metamorphism in the Mount Isa and George Fisher Zn-Pb-Cu-Ag deposits, Australia, by paleomagnetism. American Geophysical Union, Fall Meeting 2010, Abstract GP33C-0953. Painter et al. (1999) - Sedimentologic, petrographic, and sulfur isotope constraints on fine-grained pyrite formation at Mount Isa Mine and environs, northwest Queensland, Australia. Economic Geology 94: 883-912. Photo gallery of pyrite: www.mindat.org/gallery.php?min=3314

musée Australie États-Unis
This image shows a 2.1 billion year old rock containing black-banded ironstone. The rock weighs about 8.5 tons, and is approximately two meters high, three meters wide, and one meter thick. It was found in North America and belongs to the National Museum of Mineralogy and Geology, Dresden, Germany. The rock is located at +51°2'34.84" +13°45'26.67".
Intervalles Rhyacian

This image shows a 2.1 billion year old rock containing black-banded ironstone. The rock weighs about 8.5 tons, and is approximately two meters high, three meters wide, and one meter thick. It was found in North America and belongs to the National Museum of Mineralogy and Geology, Dresden, Germany. The rock is located at +51°2'34.84" +13°45'26.67".

musée Allemagne géologie
Brachylophosaurus canadensis TMP 1990.104.0001, Oldman Formation, Milk River, Alberta. Original, not cast. At the Royal Tyrrell Museum of Palaeontology.

Brachylophosaurus canadensis TMP 1990.104.0001, Oldman Formation, Milk River, Alberta. Original, not cast. At the Royal Tyrrell Museum of Palaeontology.

musée Milk River Oldman moulage +2
Brachylophosaurus canadensis TMP 1990.104.0001, Oldman Formation, Milk River, Alberta. Original, not cast. At the Royal Tyrrell Museum of Palaeontology.

Brachylophosaurus canadensis TMP 1990.104.0001, Oldman Formation, Milk River, Alberta. Original, not cast. At the Royal Tyrrell Museum of Palaeontology.

musée Milk River Oldman moulage +2
Title: Dinosaur hunting in western Canada
Identifier: dinosaurhuntingi00russ (find matches)
Year: 1966 (1960s)
Authors: Russell, Loris Shano, 1904-; Royal Ontario Museum
Subjects: Dinosaurs; Paleontology
Publisher: (Toronto : Printed at the University of Toronto Press)
Contributing Library: ROM - University of Toronto
Digitizing Sponsor: University of Toronto

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image: 
This season of 1921 George Sternberg became the first dinosaur col- lector on the Red Deer River to have his work recorded in motion pictures. This happened by a curious error. The Dominion Motion Picture Bureau, predecessor of the National Film Board of Canada, had decided to make a short motion picture based on the work being done by the Geological Survey of Canada in the collecting and displaying of Canadian dinosaurs. The camera party sent to Alberta was naturally supposed to visit the Geological Survey party under Charles M. Sternberg, but local directions sent them to the camp of George Sternberg. So this excellent little film records field work by the University of Alberta party and preparation being done at the National Museum of Canada in Ottawa. That winter George Sternberg continued the preparation of the speci- mens obtained during the two preceding field seasons, but in the spring he resigned to accept a position with the Field Museum of Natural History of Chicago, under Elmer S. Riggs. The summer of 1922 was the last time that the eldest of the Sternberg sons worked on the Red Deer River, his collec- tion going to Chicago. However, he returned to Edmonton for several months in 1935, to complete the preparation of the collection that he brought together in 1920 and 1921. When George Sternberg left the Geological Survey of Canada in 1918, the only one of the four Sternbergs remaining at Ottawa was Charles Mortram Sternberg, the second son of C. H. Sternberg. Actually, Charles had his first independent expedition to the Red Deer badlands in 1917, C. M. Sternberg ami G. E. Lindblad working on the skull of a horned dinosaur (Centrasaurus sp.), Oldman formation, Red Deer River, 1917. N.M.C., No. 39994.
Text Appearing After Image: 
22

Note About Images

Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.

Title: Dinosaur hunting in western Canada Identifier: dinosaurhuntingi00russ (find matches) Year: 1966 (1960s) Authors: Russell, Loris Shano, 1904-; Royal Ontario Museum Subjects: Dinosaurs; Paleontology Publisher: (Toronto : Printed at the University of Toronto Press) Contributing Library: ROM - University of Toronto Digitizing Sponsor: University of Toronto View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: This season of 1921 George Sternberg became the first dinosaur col- lector on the Red Deer River to have his work recorded in motion pictures. This happened by a curious error. The Dominion Motion Picture Bureau, predecessor of the National Film Board of Canada, had decided to make a short motion picture based on the work being done by the Geological Survey of Canada in the collecting and displaying of Canadian dinosaurs. The camera party sent to Alberta was naturally supposed to visit the Geological Survey party under Charles M. Sternberg, but local directions sent them to the camp of George Sternberg. So this excellent little film records field work by the University of Alberta party and preparation being done at the National Museum of Canada in Ottawa. That winter George Sternberg continued the preparation of the speci- mens obtained during the two preceding field seasons, but in the spring he resigned to accept a position with the Field Museum of Natural History of Chicago, under Elmer S. Riggs. The summer of 1922 was the last time that the eldest of the Sternberg sons worked on the Red Deer River, his collec- tion going to Chicago. However, he returned to Edmonton for several months in 1935, to complete the preparation of the collection that he brought together in 1920 and 1921. When George Sternberg left the Geological Survey of Canada in 1918, the only one of the four Sternbergs remaining at Ottawa was Charles Mortram Sternberg, the second son of C. H. Sternberg. Actually, Charles had his first independent expedition to the Red Deer badlands in 1917, C. M. Sternberg ami G. E. Lindblad working on the skull of a horned dinosaur (Centrasaurus sp.), Oldman formation, Red Deer River, 1917. N.M.C., No. 39994. Text Appearing After Image: 22 Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.

chasse film musée Canada +1
Brachylophosaurus canadensis skull (original). From the Oldman Formation, Milk River, Alberta. On display at the Royal Tyrrell Museum, Alberta, Canada.

Brachylophosaurus canadensis skull (original). From the Oldman Formation, Milk River, Alberta. On display at the Royal Tyrrell Museum, Alberta, Canada.

musée Canada Milk River Oldman +3
Brachylophosaurus canadensis (TMP 2005.000.0029), Royal Tyrrell Museum, Drumheller, Alberta, 2025-07-13; cast, Campanian, from the Oldman Formation
Formations Oldman

Brachylophosaurus canadensis (TMP 2005.000.0029), Royal Tyrrell Museum, Drumheller, Alberta, 2025-07-13; cast, Campanian, from the Oldman Formation

musée Oldman Campanien moulage +2
Psittacosaurus skeletal mount (Early Cretaceous, Jiufotang Formation) and unidentified Late Cretaceous dinosaur egg from Xixia, Hennan, on display in the Li Siguang Memorial Museum in Huangzhou.
Formations Jiufotang

Psittacosaurus skeletal mount (Early Cretaceous, Jiufotang Formation) and unidentified Late Cretaceous dinosaur egg from Xixia, Hennan, on display in the Li Siguang Memorial Museum in Huangzhou.

musée Jiufotang Crétacé Crétacé inférieur +4
Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA)
A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties.  At its simplest, a mineral is a naturally-occurring solid chemical.  Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common.  Mineral classification is based on anion chemistry.  Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.
The silicates are the most abundant and chemically complex group of minerals.  All silicates have silica as the basis for their chemistry.  "Silica" refers to SiO2 chemistry.  The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4.  Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon.  The resulting formula for silica is thus SiO2, not SiO4.
Opal is hydrous silica (SiO2·nH2O).  Technically, opal is not a mineral because it lacks a crystalline structure.  Opal is supposed to be called a mineraloid.  Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM).
Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence).  This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids.  Different opalescent colors are produced by colloids of differing sizes.  If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced.  Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979).
Not all opals have the famous play of colors, however.  Common opal has a wax-like luster & is often milky whitish with no visible color play at all.  Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture.
Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians.  Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass.  Sometimes, fossils are preserved in opal or precious opal.
The precious opal shown above is surrounded by silicified claystone.  The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks.
Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous
Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia


Photo gallery of opal:
<a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a>


References cited:

Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program.  Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51.  68 pp.

Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. Opal is hydrous silica (SiO2·nH2O). Technically, opal is not a mineral because it lacks a crystalline structure. Opal is supposed to be called a mineraloid. Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM). Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence). This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids. Different opalescent colors are produced by colloids of differing sizes. If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced. Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979). Not all opals have the famous play of colors, however. Common opal has a wax-like luster & is often milky whitish with no visible color play at all. Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture. Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians. Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass. Sometimes, fossils are preserved in opal or precious opal. The precious opal shown above is surrounded by silicified claystone. The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks. Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia Photo gallery of opal: <a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a> References cited: Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program. Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51. 68 pp.

musée Australie États-Unis Denver
Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA)
A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties.  At its simplest, a mineral is a naturally-occurring solid chemical.  Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common.  Mineral classification is based on anion chemistry.  Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.
The silicates are the most abundant and chemically complex group of minerals.  All silicates have silica as the basis for their chemistry.  "Silica" refers to SiO2 chemistry.  The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4.  Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon.  The resulting formula for silica is thus SiO2, not SiO4.
Opal is hydrous silica (SiO2·nH2O).  Technically, opal is not a mineral because it lacks a crystalline structure.  Opal is supposed to be called a mineraloid.  Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM).
Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence).  This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids.  Different opalescent colors are produced by colloids of differing sizes.  If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced.  Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979).
Not all opals have the famous play of colors, however.  Common opal has a wax-like luster & is often milky whitish with no visible color play at all.  Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture.
Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians.  Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass.  Sometimes, fossils are preserved in opal or precious opal.
The precious opal shown above is surrounded by silicified claystone.  The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks.
Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous
Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia


Photo gallery of opal:
<a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a>


References cited:

Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program.  Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51.  68 pp.

Precious opal from Australia. (public display, Denver Museum of Nature & Science, Denver, Colorado, USA) A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 4900 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates. The silicates are the most abundant and chemically complex group of minerals. All silicates have silica as the basis for their chemistry. "Silica" refers to SiO2 chemistry. The fundamental molecular unit of silica is one small silicon atom surrounded by four large oxygen atoms in the shape of a triangular pyramid - this is the silica tetrahedron - SiO4. Each oxygen atom is shared by two silicon atoms, so only half of the four oxygens "belong" to each silicon. The resulting formula for silica is thus SiO2, not SiO4. Opal is hydrous silica (SiO2·nH2O). Technically, opal is not a mineral because it lacks a crystalline structure. Opal is supposed to be called a mineraloid. Opal is made up of extremely tiny spheres (colloids - <a href="https://www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg" rel="nofollow">www.uwgb.edu/dutchs/acstalks/acscolor/OPALSPHR.jpg</a>) that can be seen with a scanning electron microscope (SEM). Gem-quality opal, or precious opal, has a wonderful rainbow play of colors (opalescence). This play of color is the result of light being diffracted by planes of voids between large areas of regularly packed, same-sized opal colloids. Different opalescent colors are produced by colloids of differing sizes. If individual colloids are larger than 140 x 10-6 mm in size, purple & blue & green colors are produced. Once colloids get as large as about 240 x 10-6 mm, red color is seen (Carr et al., 1979). Not all opals have the famous play of colors, however. Common opal has a wax-like luster & is often milky whitish with no visible color play at all. Opal is moderately hard (H = 5 to 6), has a white streak, and has conchoidal fracture. Several groups of organisms make skeletons of opaline silica, for example hexactinellid sponges, diatoms, radiolarians, silicoflagellates, and ebridians. Some organisms incorporate opal into their tissues, for example horsetails/scouring rushes and sawgrass. Sometimes, fossils are preserved in opal or precious opal. The precious opal shown above is surrounded by silicified claystone. The rock is from the Griman Creek Formation, a Cretaceous-aged succession of nonmarine, fine-grained and coarse-grained siliciclastic sedimentary rocks. Stratigraphy: Griman Creek Formation, Albian Stage, upper Lower Cretaceous Locality: Coocoran Opal Field, west-southwest of Coocoran Lake, northern New South Wales, eastern Australia Photo gallery of opal: <a href="http://www.mindat.org/gallery.php?min=3004" rel="nofollow">www.mindat.org/gallery.php?min=3004</a> References cited: Carr et al. (1979) - Andamooka opal fields: the geology of the precious stones field and the results of the subsidised mining program. Geological Survey of South Australia Department of Mines and Energy Report of Investigations 51. 68 pp.

musée Australie États-Unis Denver
Fossil eggs of the oospecies Macroelongatoolithus carlylei (believed to be the eggs of giant oviraptorosaurs) from the Cedar Mountain Formation of North America. At the SECU Dinolab of the North Carolina Museum of Natural Sciences

Fossil eggs of the oospecies Macroelongatoolithus carlylei (believed to be the eggs of giant oviraptorosaurs) from the Cedar Mountain Formation of North America. At the SECU Dinolab of the North Carolina Museum of Natural Sciences

musée Cedar Mountain fossile Macroelongatoolithus +2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Actualités

Germany’s Famous Fossil Beds Yield New Species of Jurassic Ichthyosaur
Les célèbres gisements de fossiles d’Allemagne donnent naissance à de nouvelles espèces d’ichtyosaures jurassiques
musée Allemagne Jurassique fossile Ichthyosauria Ichthyosaurus Jabalisaurus nouvelle espèce
Le Dr Erin Maxwell du Staatliches Museum für Naturkunde Stuttgart et ses collègues ont identifié une deuxième espèce dans les gisements calcaires allemands de Plattenkalk : Jabalisaurus tethyensis. L’article Les célèbres gisements de fossiles d’Allemagne produisent de nouvelles espèces d’ichtyosaures jurassiques est apparu en premier sur Sci.News : Breaking Science News.
11/08/2026 sci-news ⚙ Traduction automatique
Des scientifiques redécouvrent des fossiles perdus de Megalodon et révèlent un géant de 79 pieds
vertèbre musée fossile
Plusieurs énormes vertèbres de Megalodon, qui auraient été détruites en 1989, ont été retrouvées inaperçues sur une étagère de musée. Leur analyse renforce la preuve que le requin géant pourrait dépasser 24 mètres (79 pieds) de longueur et vivre près d'un siècle. Les chercheurs estiment également que ses nouveau-nés auraient pu mesurer une taille étonnante de 3,6 mètres (12 pieds).
07/08/2026 sciencedaily ⚙ Traduction automatique
Ce « crocodile terroriste » de la taille d’un autobus scolaire a mangé des dinosaures. Maintenant c'est de retour
musée fossile Dinosauria Géorgie squelette
Un crocodile massif capable d'attaquer les dinosaures a été ramené à la vie en tant que premier squelette monté scientifiquement précis de Deinosuchus schwimmeri. La réplique de 31 pieds du Tellus Science Museum de Géorgie a été construite à partir d’analyses détaillées de fossiles et de plus de 40 ans de recherches menées par le paléontologue Dr David Schwimmer, en l’honneur duquel l’espèce doit son nom.
05/08/2026 sciencedaily ⚙ Traduction automatique
L’audition sous-marine des phoques expliquée par de nouvelles recherches
musée évolution mammifères étude
Une équipe de scientifiques internationaux a découvert le mécanisme remarquable derrière l’audition sous-marine des phoques. Une nouvelle étude, menée par des chercheurs du Musée d'histoire naturelle de Londres, révèle que les phoques existants entendent aussi bien dans l'air que sous l'eau. Les résultats aident à expliquer un mystère évolutif de longue date et pourraient soutenir les futurs efforts de conservation. La recherche, publiée
16/07/2026 everythingdinosaur ⚙ Traduction automatique
Il devient le dinosaure le plus cher du monde en 10 minutes : voici l’incroyable histoire de Gus
Il devient le dinosaure le plus cher du monde en 10 minutes : voici l’incroyable histoire de Gus
musée Dinosauria Tyrannosaurus squelette
Il a traversé 67 millions d’années enfoui dans le sol avant de faire trembler une salle des ventes. Le squelette de Tyrannosaurus rex surnommé "Gus" a été adjugé 50,13 millions de dollars chez Sotheby’s, à New York. Un record absolu pour un dinosaure, qui ravive le débat sur la privatisation des...
15/07/2026 futura-terre
1 2 3 4 5