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GeoDIL Images

University of North Dakota

The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota (UND) in fall 2000. Dexter Perkins and Joseph Hartman, of UND's Department of Geology and Geological Engineering, are the Library Directors.



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GeoDIL Images
by Darla Sondrol
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Cobaltite, Gorden Lake, Ontario Description: The metallic silver mineral with the slighlty pinkish tinge is cobaltite, (Co,Fe)AsS, cobalt iron arsenic sulfide. It is rare but is still an important cobalt ore mineral. Here it is accompanied by a green unidentified secondary mineral that has filled cracks between cobaltite crystals. This specimen is 9 cm long. Location: Canada ▹ Ontario. Near Gorden Lake. Collection: University of North Dakota Mineralogy Collection #227. Tech details: 981 KB....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of hornblende andesite Description: This is a cross polarized thin section of hornblende andesite. Abundant oscillatory-zoned plagioclase with glomeroporphritic amphibole set in a fine-grained, plagioclase-rich groundmass. Amphiboles show dark reaction rims. Minor amounts of unaltered augite are present. Magnetite is an accessory. Chronostratigraphy: Triassic. Geologic province: Excelsior. Location: USA ▹ Nevada ▹ Mineral Collection: Ward’s Collection of Classic North...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Ullmanite from Siegen, Westphalia Description: Ullmanite, NiSbS (nickel antimony sulfide), is a rare nickel mineral that belongs to the Cobaltite Group of minerals. Most members of this group are rare to extremely rare, except for cobaltite. Like other members of this group, ullmannite can form nice crystals that are either cubic, octahedral, tetrahedral or even pyritohedral, the classic crystal form of pyrite. This sample is 13 cm across. Location: Westphalia. Near Siegen. Collection:...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Martite Description: Martite is hematite, Fe 2 O 3 (iron oxide), that is pseudomorphic after magnetite, and it is characterized by its fine-grained polycrystalline nature. Location: Peru. Near Arequipa. Collection: University of North Dakota Mineralogy Collection #370. Tech details: 624 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Euchroite Description: Euchroite, Cu 2 (AsO 4 )(OH)·3H 2 O, is a copper arsenate hydroxide hydrate mineral. It is known for its bright green color and is considered very rare. Location: Hungary. Near Libethen. Collection: University of North Dakota Mineralogy Collection #1030. Tech details: 625 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera, 60mm Nikon AF micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Pink Tourmaline Description: Tourmalines are a favorite among mineral collectors. Their rich and varied colors can captivate the eye. Even the black opaque tourmalines can shine nicely and produce sharp crystal forms. Tourmalines are cut as precious gems, carved into figurines, cut as cabochons, sliced into cross-sections and natural specimens are enthusiastically added to many collections. Tourmaline is one of the few common minerals containing boron. This is a round cut pink tourmaline being...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Magnetite with franklinite Description: Magnetite, Fe 3 O 4 , (iron oxide), is a natural magnet, hence the name, giving it a very nice distinguishing characteristic. Here it is seen with franklinite (zinc iron manganese oxide). This sample is only 11 cm in length, yet due to the magnetite, it is extremely heavy. Location: USA ▹ New Jersey. Near Franklin. Franklin Furnace. Collection: University of North Dakota Mineralogy Collection #996. Tech details: 629 KB. Hand specimen. Fujifilm FinePix...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Oolitic hematite from unknown location Description: Hematite, Fe 2 O 3 (iron oxide), has historically been a very important ore of iron. The picture shows an oolitic form of hematite. It is composed of oolites , small reddish brown rounded grains cemented tightly together. The specimen is 11.5 cm across. Collection: University of North Dakota Mineralogy Collection #5012. Tech details: 829 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Jarosite from near Chuquicamata, Chile Description: Jarosite is an uncommon potassium iron sulfate hydroxide. It can be brown, yellow, yellow brown, or light yellow, and is a secondary mineral that forms by weathering in arid climates. This specimen is about 5 cm across. Location: Chile ▹ Antofagasta. Near Chuquicamata. Collection: University of North Dakota Mineralogy Collection. Tech details: 648 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60 mm AF Nikon micro lens. The...
Topics: geology, mineralogy
GeoDIL Images
by Shannon Heinle
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Diopside Description: Diopside is a calcium magnesium silicate. Diopside is an important rock forming mineral in several metamorphic and basic to ultra basic igneous rocks, also found in meteorites. Diopside is a part of an important solid solution series of the pyroxene group. Diopside is the magnesium rich end member of the series. Diopside has several varieties, including a chromium-rich gem variety called chrome diopside, violan is a rare blue variety found in some localities in Italy....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Hematite from Scranton, Minnesota Description: Hematite, Fe 2 O 3 (iron oxide), is sometimes an important ore of iron. It is also used as a pigment. Hematite gets its name from a Greek word meaning blood-like , because of the color of its powder. Ancient superstition held that large deposits of hematite formed from blood where battles were fought. This specimen is about 6 cm across. Location: USA ▹ Minnesota. Near Scranton. Collection: University of North Dakota Mineralogy Collection #389....
Topics: geology, mineralogy
GeoDIL Images
by Dexter Perkins
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Limestone sea arch, south coast, Portugal Description: This photo shows a small sea arch, cut through limestone, near the southernmost point of Portugal. Location: Portugal Tech details: 462 KB. Outcrop. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota (UND) in fall 2000. Dexter Perkins and Joseph Hartman, of...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Coarsely crystalline epidote from Peru Description: This specimen, 9 cm in longest dimension, contains mostly radiating crystals of dark green-black epidote, Ca 2 (Al,Fe) 3 Si 3 O 12 (OH). Minor quartz (clear, white) is also present. Epidote is typically fine grained or massive with a “pistachio” color. When in radiating aggregates, such as this specimen, the color generally appears darker. Location: Peru. Near Mina Rasario Mabel Huancavelica. Collection: University of North Dakota...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Tongue River Formation Description: Tongue River Formation exposure near an abandoned mine in Ward County, ND. Road access to mine goes directly above exposure and shell bed. Lithostratigraphy: Tongue River Formation. Location: USA ▹ North Dakota ▹ Ward County. Near Minot. L194, Highway 83. Collection: Joseph Hartman P02408. Tech details: 353 KB. Outcrop. Kodachrome, TIFF. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Pyroaurite from Langban, Sweden Description: Pyroaurite, is a magnesium iron hydroxycarbonatehydrate and has the chemical formula of Mg 6 Fe 2 (OH) 16 CO 3 ·4H 2 O. It most commonly occurs as a secondary mineral, forming in veins or coatings associated with Mg-rich rocks. The largest of the pieces shown is 1 cm across. This specimen comes from a mine near Langban, Sweden. Location: Sweden. Near Langban. Collection: University of North Dakota Mineralogy Collection #730. Tech details: 193 KB....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Aragonite from Asni, Morocco Description: Aragonite has composition CaCO 3 , and is less common than its polymorph (different crystal structure but same composition) calcite. Aragonite's most famous crystal habit involves pseudo-hexagonal prismatic crystals like the ones shown here. This specimen, 8 cm across, comes from the classic collecting site at Asni, Morocco. Location: Morocco. Near Asni. Collection: University of North Dakota Mineralogy Collection. Tech details: 406 KB. Hand specimen....
Topics: geology, mineralogy
GeoDIL Images
by Dexter Perkins
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Folded sediments, Orocopia Mountains Description: Folded sediments, Orocopia Mountains south of Joshua Tree National Park. Location: USA ▹ California. Near Palm Springs. Collection: E441130991V. Tech details: 384 KB. Vista. Canon Eos Rebel, 55mm lens, Kodak Ektachrome Elite. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Tilted strata of the Uinta Mountains, Flaming Gorge, Wyoming Description: Tilted strata of the Uinta Mountains, Flaming Gorge, Wyoming. Geologic province: Uinta Mountains. Location: USA ▹ Wyoming. Uinta Mountains. Collection: Joseph Hartman P02657. Tech details: 242 KB. Outcrop. Kodachrome, TIFF format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Soda-niter from Tarapaca, Chile Description: Soda-niter, NaNO 3 , is also called nitratine. It easily dissolves in water and sometimes deliquesces in humid conditions, so it is not very common. It is only found in arid, desert regions or as efflorescences on dry cave or mine walls. The largest of these pieces is 9 cm across. Location: Chile. Near Tarapaca. Collection: University of North Dakota Mineralogy Collection #602. Tech details: 504 KB. Hand specimen. Fujifilm FinePix S1Pro digital...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Prenhite Description: Prehnite, Ca 2 A l2 Si 3 O 10 (OH) 2 (calcium aluminum silicate hydroxide), is an attractive mineral and is occassionally used for ornamental stone purposes. Typical prehnite forms rather thick crusts with a rough or crystaline texture. The color is usually a pleasant green and is at times distinctive of prehnite. Other similar minerals include gyrolite, smithsonite and hemimorphite. Prehnite is harder than these and lacks smithsonites luster. Hemimorphite is usually blue...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Native sulfur on limestone Description: This sample contains yellow sulfur on a gray limestone. It is about 15 cm across. Sulfur, an important industrial mineral, is often found associated with carbonate rocks. Location: Sicily Collection: University of North Dakota Mineralogy Collection #55. Tech details: 595 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Aurichalcite from Magdalena, New Mexico Description: The blue-green mineral is aurichalcite, (Zn,Cu) 5 (CO 3 ) 2 (OH) 6 (zinc copper carbonate hydroxide). Here it is associated with limonite and goethite. It is often found with other colorful minerals such as azurite, smithsonite and malachite. Aurichalcite forms in the oxidation zones of zinc-copper deposits. Crystals are acicular or fibrous and often found in tufted aggregates or coatings. Typical colors are blue to blue-green to grass green....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Native tellurium, Montezuma Mine, Sonora, Mexico Description: This sample, 4 cm across, contains abundant gray metallic native tellurium, a very rare mineral. When it does occur, it is often found with gold and gold tellurides such as sylvanite and calaverite. The metal tellurium is mostly used in alloys with other metals. It is added to lead to improve its strength and durability. In steel and copper it makes the metals more workable. Tellurium is also used in blasting caps. Location: Mexico....
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Cinnabar with metacinnabar Description: Cinnabar (HgS) is a mercury sulfide that typically has a vermillion to pink or scarlet color. Metacinnabar (a different mineral) has the same composition but a black or gray color, and sometimes a metallic luster. Both are important ore minerals of mercury. This specimen, a fine grained mix of both minerals, is about 8 cm in longest dimension. Collection: University of North Dakota Mineralogy Collection #187. Tech details: 423 KB. Hand specimen. Fujifilm...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Faulted Upper Cretaceous Hell Creek Formation molluscan fossil locality, Charles M. Russell National Wildlife Refuge, Garfield County, Montana Description: View south of normal fault and freshwater molluscan locality in the Upper Cretaceous Hell Creek Formation badlands south of the Fort Peck Reservoir in the Charles M. Russell National Wildlife Refuge, Garfield County, Montana. Ben Shoup is sitting on the downdropped flootwall. Chronostratigraphy: Upper Cretaceous. Lithostratigraphy: Hell...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Sphalerite with chalcopyrite from Manitouwadge, Ontario Description: This sample contains mostly dark-brown to black sphalerite, (Zn,Fe)S. This variety of sphalerite is sometimes called marmatite or christophite. It generally is mostly ZnS with up to twenty percent FeS. Accompanying the sphalerite is golden-yellow chalcopyrite. The specimen is 14 cm across. Location: Canada ▹ Ontario. Near Manitouwadge. GECO Mines. Collection: University of North Dakota Mineralogy Collection #182. Tech...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Red Fleet, Chinle, Gartra Frit Description: Red Fleet, Chinle, Gartra Frit, parallel with contact of Gartra and Chinle formations. Location: USA ▹ Utah Collection: Joseph Hartman P02697 vol. 3-20. Tech details: 427 KB. Outcrop. Etkachrome; TIFF Format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota (UND) in...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Adamite Description: Adamite, Zn 2 (AsO 4 )(OH) (zinc arsenate hydroxide), is a favorite among collectors of fluorescent minerals because of its consistent bright green fluorescence under short and long UV light. It also makes a wonderful mineral specimen in ordinary light. The typical lime green color of its adamantine (high luster) crystals set on top of its commonly associated red limonite matrix make specimens particularly attractive. Location: Greece. Near Laurium. Collection: University...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Saint Peter Sandstone, Minnesota Description: Saint Peter Sandstone, Minnesota. Chronostratigraphy: Middle Ordovician. Lithostratigraphy: Saint Peter Sandstone. Geologic province: Hollendale Embayment. Location: USA ▹ Minnesota Collection: Joseph Hartman P00958. Tech details: 241 KB. Outcrop. Kodachrome, TIFF format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of diorite Description: This is a cross polarized thin section of diorite. Green hornblende, the dominant species, contributes to a moderately well-developed gneissoid foliation in subparallel subhedra, partly replaced by biotite, in both anhedral patches and euhedral tablets. The medium plagioclase in anhedral, slightly zoned gradationally and locally has central parts sericitized. Large sphene euhedra from a conspicuous accessory. Others are epidote, rare allanite, apatite and...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of nepheline syenite (malignite) Description: This is a photo of a cross polarized thin section of nepheline syenite (malignite). Nearly half of the rock is composed of euhedral to subhedral, elongated, pale brownish-yellow acmite prisms. Simple and lamellar twinning and zoning is present in some crystals, and grains exhibit a somewhat preferred orientation. Low birefringence nepheline and sanidine make up the other essential minerals. Grains are mostly subhedral and commonly...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Fossil Forest and Stratigraphy Near the Cliffs of Fruitland and Kirtland, New Mexico Description: Fossil Forest and Stratigraphy Near the Cliffs of Fruitland and Kirtland, New Mexico. Location: USA ▹ New Mexico Collection: Joseph Hartman P02884 (1980 June-August). Tech details: 331 KB. Vista. Kodachrome, TIFF format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Upper Cretaceous Fox Hills (marine)-Hell Creek (nonmarine) formational contact Description: View southeast of Upper Cretaceous Fox Hills (marine)-Hell Creek (nonmarine) formational contact, Garfield County, Montana. View includes cross-bedded marine sandstones of the Fox Hills and river channel deposits of basal Hell Creek. Chronostratigraphy: Upper Cretaceous, Maastrichtian. Lithostratigraphy: Fox Hills, Hell Creek. Geologic province: Williston Basin. Location: USA ▹ Montana ▹ Garfield....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Magnetite Description: Magnetite, Fe 3 O 4 (iron oxide), is a mineral that has a very high iron content. Magnetite has a black or brownish-red color and a black streak. It has a hardness of about 6 on the Mohs hardness scale. It is one of two minerals in the world that is naturally magnetic. Magnetite, also known as lodestone, is found throughout the United States. Magnetite is an important source of iron ore and occurs in many igneous rocks. Location: USA ▹ Colorado. Near Golden. Collection:...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Upper Cretaceous Hell Creek Formation fossil locality Description: Upper Cretaceous Hell Creek Formation dinosaur ( Triceratops )and freshwater molluscan fossil locality, Garfield County, Montana. Chronostratigraphy: Upper Cretaceous, Maastrichtian. Lithostratigraphy: Hell Creek Formation. Geologic province: Williston Basin. Location: USA ▹ Montana ▹ Garfield. Near Jordan. Collection: Joseph Hartman C07129. Tech details: 642 KB. Outcrop. Kodachrome, TIFF format. The Geoscience Digital Image...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Owyheeite with quartz and pyrite Description: Owyheeite, Ag 2 Pb 7 (Sb,Bi) 8 S 20 , is a lead silver antmony bismuth sulfide that usually occurs as compacted fibers. Location: USA ▹ Nevada ▹ Nye County. Near Morey District. Collection: University of North Dakota Mineralogy Collection #273. Tech details: 730 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Paleontology of Fossil Forest, New Mexico Description: Paleontology of Fossil Forest, New Mexico. Location: USA ▹ New Mexico Collection: Joseph Hartman P02884 (1980 June-August). Tech details: 492 KB. Outcrop. Kodachrome, TIFF format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota (UND) in fall 2000. Dexter...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Upper Cretaceous freshwater unionids (mollusks, clams) from the Fossil Forest locality, Fruitland Formation, New Mexico Description: Upper Cretaceous freshwater unionids (mollusks, clams) from the Fossil Forest locality near adjacent cliff, Fruitland Formation, New Mexico. Chronostratigraphy: Upper Cretaceous, Maastrichtian. Lithostratigraphy: Fruitand Formation. Geologic province: San Juan Basin. Location: USA ▹ New Mexico ▹ San Juan. Fossil Forest site. Collection: Joseph Hartman P02943....
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Exposure of the Odanah Member of the Pierre Formation, North Dakota Description: The Odanah Member is exposed in a shale pit on the north side of the road. The unit was deposited in a shallow-water marine environment during the Cretaceous about 71 to 74 million years ago (interpreted from Hardenbol et al., 1998). The Odanah Member is a hard, siliceous, light-gray shale and forms conspicuous cliffs. It is locally quarried for road-surfacing material. Fossils are scarce in the Odanah, although...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Ruby and zoisite Description: Ruby (Al 2 O 3 ) is created when zoisite (Ca 2 Al 3 (SiO 4 ) 3 (OH)) is heat treated. The green color mineral is zoisite and the red is the ruby. This rock is about 9.5 cm on its longest axis. This rock is courtesy of: The Jewel Box , Grand Forks, ND. Collection: The Jewel Box Collection of Rocks. Tech details: 463 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Mylonite, Los Angeles County, California Description: Mylonites form as a result of dyanmic metamorphism. They may be breccia-like, or streaked or banded. Mylonites result from grinding, granulation, pulverization and shearing during faulting. This sample is a jumble of rock and mineral fragments (up to 3 mm across) in a fine grained matrix. The fragments include mostly quartz and plagioclase with lesser amounts of biotite, hornblende and sphene. The matrix includes the same minerals,...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Brochantite from Chuquicamata, Chile Description: Brochantite (the green mineral) is a copper sulfate hydroxide, having general formula Cu 4 SO 4 (OH) 6 . It forms by oxidation of copper ore minerals and is hard to distinguish from some other secondary copper minerals. It typically occurs as acicular (needle-like) or fibrous crystals forming coatings and tufts. The red material is probably cuprite, CuO. These are both important copper ore minerals in some deposits. Location: Chile ▹...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of phonolite Description: This is a cross polarized thin section of phonolite. The few phenocrysts are tablets of anorthoclase (“Moire-type” extinction). The trachytic-textured matrix consists of parallel thin orthoclase crystals, stubby nepheline euhedra and aegirine microlites in plumose clusters. Accessories are magnetite, pyrite and analcime. Chronostratigraphy: Tertiary (Post-Oligocene). Location: USA ▹ Colorado ▹ Teller. Near Cripple Creek. Beacon Hill. Collection:...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of hornblende gabbro Description: This is a cross polarized thin section of hornblende gabbro. An equiangular rock consisting of subhedral labradorite tablets and somewhat subordinate mafics augite, hornblende, magnetite in anhedral clustered grains. The plagioclase shows narrow marginal zoning. The augite is strongly uralitized by olive green hornblende. The opaques are an intergrowth of predominant granular magnetite and subordinate pyrite. Other accessories are biotite, apatite,...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Pink Diamond Description: Diamond, elemental carbon (C), is the hardest substance found in nature, diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). Diamond comes from the Greek word “adamas,” meaning “I tame.” The beautiful hues of colored diamonds are caused by the presence and distribution of small amounts of nitrogen (yellow) or boron (blue) within the diamond. This sample is a princess cut diamond, with the color/clarity rating being...
Topics: geology, mineralogy
GeoDIL Images
by Shannon Heinle
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Garnet, muscovite and quartz in pegmatite Description: Red garnet is accompanied by muscovite, K-feldspar and quartz in this sample from a pegmatite. The specimen is about 10 cm across. Collection: University of North Dakota Mineralogy Collection #1790. Tech details: 737 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Ankerite from near Freiburg, Germany Description: This sample, abaout 12 cm across, contains small crystals of transparent ankerite. The specimen is actually upside down; the ankerite precipitated on stalactitic limestone. Ankerite's ideal formula is CaFe(CO 3 ) 2 but there is always a significant amount of magnesium amd manganese substitution for the iron. Location: Germany. Near Freiberg. Collection: University of North Dakota Mineralogy Collection #671. Tech details: 623 KB. Hand specimen....
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Upper Cretaceous Hell Creek Formation fossil locality, Garfield County, Montana Description: General view east of a invertebrate and vertebrate fossil locality in isolated butte in the Upper Cretaceous Hell Creek Formation, Garfield County, Montana. Chronostratigraphy: Upper Cretaceous, Maastrichtian. Lithostratigraphy: Hell Creek. Geologic province: Williston Basin. Location: USA ▹ Montana ▹ Garfield. Near Jordan. Collection: Joseph Hartman C07123. Tech details: 541 KB. Outcrop....
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Prehnite, calcite and apophyllite Description: Prehnite, calcite and apophyllite are all visible in this 7 cm sample. Prehnite, Ca 2 A l2 Si 3 O 10 (OH) 2 (calcium aluminum silicate hydroxide), is the distinctive color green, while the lighter calcite and apophyllite can be harder to tell apart. Location: USA ▹ Massachusetts. Near Notch. Collection: University of North Dakota Mineralogy Collection #1740. Tech details: 626 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of granodiorite Description: Granodiorite thin section in cross polarized light. Of the essential species, only plagioclase is euhedral. The mafics are subhedral and tend to be clustered. The quartz is undulatory. The plagioclase is strongly and complexly zoned with some thin zones selectivley sericitized. The subordinate potash feldspar is microcline perthite. Closely associated with the biotite are the accessories apatitie, zircon and magnetite. The pale green hornblende contains...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Barite, BaSO 4 Description: This sample of barite comes from an unknown location. It is about 5 cm across. This sort of aggregate of plates or blades is common for coarsely crystalline barite. Collection: University of North Dakota Mineralogy Collection #1780. Tech details: 589 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Malachite Description: Malachite, Cu 2 (CO 3 )(OH) 2 (copper carbonate hydroxide), is a famous and very popular semi-precious stone. It is named for the Greek word for “mallow”, a green herb. The light and dark green bands are so distictive that malachite maybe one of the most easily recognized minerals by the general public. Location: Zaire ▹ Katanga District Collection: Ward’s Classroom Collection of Gem Minerals #32. Tech details: 523 KB. Hand specimen. Fujifilm FinePix S1Pro digital...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Thin section of alkalic syenite Description: Thin section of alkalic syenite in plain polarized light. Strongly developed flow texture from the subparallel orientation of slender feldspar laths; clear sodic orthoclase (carlsbad twinning) and turbid sodic plag. (fine albite twinning). A few blocky nepheline grains, and scarce anhedra of sodalite (isostropic) also appear. Pale green augite with narrow bright green (aegirinitic) rims is the main mafic, forming euhdra of varying biotite and include...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Wollastonite with garnet and diopside Description: This is a sample of wollastonite ore from a mine at Willsboro, New York. The white wollastonite is accompanied by red garnet(grossular) and green diopside. The diopside crystals are about 1 mm in longest dimension. Lithostratigraphy: Precambrian. Geologic province: Grenville. Location: USA ▹ New York ▹ Essex. Near Willsboro. Willsboro Wollastonite Mine. Collection: University of North Dakota Mineralogy Collection #6361. Tech details: 928...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Colusite, Cu 3 (As,Sn,V,Fe,Te)S 4 Description: Colusite, Cu 3 (As,Sn,V,Fe,Te)S 4 , is the dark colored mineral; quartz is the white mineral. Colusite is typcially brownish to bronze-colored. It is a sulfide of copper and arsenic with vanadium, iron, and tellurium substituting for some of the arsenic. Here it is in visible crystals, but a massive form is more typical. It is found with other sulfides in hydrothermal copper ore veins. This specimen is 2.8 cm across. Location: USA ▹ Montana. Near...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Red Fleet, Chinle-Nugget Description: Red Fleet, Chinle-Nugget contact at top of maroon shale and of rain staining on Nuggett Formation. Location: USA ▹ Utah Collection: Joseph Hartman P02706 vol. 3-43. Tech details: 277 KB. Outcrop. Etkachrome; TIFF Format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Metamorphic and Igneous Rocks (Precambrian) of the Grand Canyon National Park, Arizona Description: View of the Grand Canyon with exposed Precambrian metamorphic and igneous rocks, which are highly deformed and tilted beds. They are heavily intruded with phanerozoic rocks capping the highest rocks on the canyon rims. Chronostratigraphy: Precambrian. Geologic province: Colorado Plateau. Location: USA ▹ Arizona. Grand Canyon. Collection: Joseph Hartman PO2479. Tech details: 254 KB. Vista....
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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Liesegang banding of Unkpapa Sandstone, Calico Canyon, Black Hills, South Dakota Description: Liesegang banding of Unkpapa Sandstone, Calico Canyon, Black Hills, South Dakota. Chronostratigraphy: Jurassic. Location: USA ▹ South Dakota ▹ Custer. Near Buffalo Gap. Boland Ridge Quadrangle. Collection: Joseph Hartman P00848. Tech details: 248 KB. Outcrop. Kodachrome, TIFF format. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Opal Description: Opal, SiO 2 -nH 2 O (hydrated silicon dioxide), is considered a mineraloid because its structure is not truly crystalline. The chemistry of opal is primarily SiO 2 and varying amounts of water from 5%-10% and greater. This water can help geologists determine the temperature of the host rock at the time the opal formed. The gem in this photo is courtesy of: The Jewel Box , Grand Forks, ND. Collection: The Jewel Box Collection of Gemstones. Tech details: 38 KB. Hand specimen....
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Joaquinite, natrolite and benitoite from San Benito County, California Description: This sample contains yellow-brown joaquinite with white natrolite and blue-green benitoite from San Benito, California, USA. Benitoite is a rare mineral having composition BaTiSi 3 O 9 . Joaquinite, also rare, has composition NaBa 2 FeCe 2 (Ti,Nb) 2 (SiO 3 ) 8 O 2 (OH,F)·H 2 O. Natrolite is a zeolite with composition Na 2 Al 2 Si 3 O 10 -2H 2 O. These minerals are only found together in San Benito California,...
Topics: geology, mineralogy
GeoDIL Images
by Joseph Hartman
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The Contact between the Niobrara and Pierre Formations, North Dakota Description: The buff-colored shale and calcareous clay seen are part of the Niobrara Formation. The Niobrara is overlain by gray shale and smooth bentonitic clay from the Pembina Member of the Pierre Formation. The contact between the 2 formations lies beneath the lowest bentonite band of the Pierre Formation. Location: USA ▹ North Dakota ▹ Cavalier. Near Vang. Vang Quadrangle. Collection: Joseph Hartman C9403. Tech...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Graywacke from Mentone, California, USA Description: Graywackes are “dirty” sandstones. That is, they are sandstones that are poorly sorted and contain significant amounts of rock fragments and clay besides the normal quartz. This sample is 9 cm across. Location: USA ▹ California Collection: Ward’s University Rock Collection #145. Tech details: 1.02 MB. Hand specimen. Fujifilm FinePix S1Pro digital. The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Stilpnomenlane schist, Laytonville Quarry, Mendocino County, California Description: This dark bronze-brown schist is from a quarry in the Franciscan Complex of California. Stilpnomelane is a relatively rare mineral, and some of the best samples come from the Franciscan, a subduction-zone-related complex that contains rocks and minerals formed by high pressure metamorphism. Besides the dominant brown stilpnomelane, this rock also contains quartz and garnet, although they are difficult to pick...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Rutheniridosmine (ruthenium-osmium-iridium alloy) in suflide ore Description: This specimen is 4 cm across. It contains rutheniridosmine, a natural alloy of ruthenium, osmium and iridium in which iridium dominates, mixed with gold-colored sulfides. When fresh, ruthenirodosmine has a silver-white metallic appearance. It occurs in ultamafic rocks and in placers derived from such rocks. Rutheniridosmine, in the past called iridosmine or osmiridium, may contain minor amounts of platinum, rhodium,...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Hanksite from Searles Lake, California, USA Description: Hanksite is one of the few minerals that belong to both the carbonate and sulfate classes. It has formula Na 22 K(SO 4 ) 9 (CO 3 ) 2 Cl. Hanksite is an evaporite mineral and often forms large geometric crystals. Associated minerals include halite, trona, borax and tincalconite. The Searles Lake playa deposits contain many other evaporite minerals too, including aphthitalite, burkeite, galeite, gaylussite, mirabilite, nahcolite,...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Native antimony with cervantite, Freiburg, Germany Description: This sample (6 cm across) contains native antimony (Sb) and cervantite (Sb 2 O 4 ). Both are gray, but the antimony has a brighter, more metallic, luster. Antimony is used in a number of industrial applications. Location: Germany. Near Freiburg. Collection: University of North Dakota Mineralogy Collection #23. Tech details: 586 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Hematite ore from the Upper Huronian Biwabik Formation, Minnesota Description: Hematite, Fe 2 O 3 (iron oxide), is an important ore of iron and it's red color makes it useful as a pigment. Hematite gets its name from a Greek word meaning blood-like because of the color of its powder. Ancient superstition held that large deposits of hematite formed from battles that were fought and the subsequent blood that flowed into the ground. Visible crystals of hematite are rare; most samples are very fine...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Chalcocite with chalcopyrite Description: Chalcocite, Cu 2 S (copper sulfide), is often found with chalcopyrite CuFeS 2 . Chalcocite is shiny and lead-gray when freshly broken, but turns black and becomes sooty when exposed to air. Chalcopyrite is yellow, sometimes slightly orangish or with a hint of green, when fresh. It may tarnish, as seen in this sample. Chalcocite and chalcopyrite are both important sources of copper (and iron). Collection: University of North Dakota Mineralogy Collection....
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Bornite from Eisleben, Germany Description: The dark colored mineral is bornite. The lighter material is mostly quartz with some sericite (white mica) mixed in. Bornite is typically dark brown or black, but may tarnish to be various shades of irredescent blue. A hint of blue can be seen in this specimen. When tarnishing produces bright colors, bornite is sometimes referred to as “peacock ore.” Bornite, a copper iron sulfide, is sometimes a major coppper ore mineral. This specimen is 7 cm...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Chalcocite from Butte, Montana Description: Chalcocite, Cu 2 S (copper sulfide), is an important copper mineral ore. Although relatively rare, it is one of the most profitable copper ore minerals because it contains lots of copper and is easy to process. Just like native copper deposits, the richest chalcocite deposits have probably been mined out, so most copper today comes from other minerals. This specimen, from the famous mining district near Butte, Montana, is about 9 cm across. If you...
Topics: geology, mineralogy
GeoDIL Images
by Dexter Perkins
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Comparison of granite (left) and arkose (right) Description: These samples of granite (on left) and arkose (on right) both contain the same minerals: predominately quartz and K-feldspar. Granite is an igneous rock, so the crystals interlock in a mosaic-like pattern. Arkose is a detrital sedimentary rock, so the crystals are piled together like grains of sand. The red color of both is due to iron oxidation. These samples are part of the Petrology teaching collection of the Department of Geology...
Topics: geology, mineralogy
GeoDIL Images
by Dexter Perkins
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Tabular barite with calcite and pyrite, from Joplin, Missouri, USA Description: Large tan barite (BaSO 4 ) tabs, some appearing pseudo-hexagonal, are embedded in finer white calcite, CaCO 3 . Pyrite crystals, FeS 2 , generally about 1 mm across are scattered in the sample. No provenance data is available except that it comes from Joplin, Missouri, USA. This photo is about 5 cm across. Location: USA ▹ Missouri. Near Joplin. Collection: University of North Dakota Mineralogy Collection. Tech...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Alunogen, Al 2 (SO 4 ) 3 ·17(H 2 O) Description: Alunogen, hydrated aluminum sulfate, is highly soluble in water. It forms as efflorescence in coal formations, as an oxidation product of sulfides in ore deposits in arid regions, or associated with fumaroles and hot springs. This sample is 8 cm across. Location: Hungary. Near Hordrizsch. Collection: University of North Dakota Mineralogy Collection #802. Tech details: 745 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon...
Topics: geology, mineralogy
GeoDIL Images
by Nessa Eull
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Rutile Description: The name is from the Latin “rutilus”, which means “golden-red”. There are three polymorphs of titanium dixoide (TiO 2 ): rutile, anatase, and brookite. Rutile is by far the most common. It is an important ore of titanium. Location: USA ▹ Pennsylvania ▹ York Collection: University of North Dakota Mineralogy Collection #481. Tech details: 764 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens. The Geoscience Digital Image Library...
Topics: geology, mineralogy
GeoDIL Images
by Darla Sondrol
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Sphaerocobaltite from Sudbury, Ontario, Canada Description: The pink mineral is sphaerocobaltite, CoCO 3 (cobalt carbonate), also sometimes called (incorrectly) cobaltocalcite and cobaltian-calcite. (The latter two names are more appropriate for referring to calcite that has an appreciable amount of cobalt in its structure as an impurity.) The sometimes deep rose-red to pink color of this mineral can be very attractive and unique. Sometimes sphaerocobaltite can be confused with other pinkinsh...
Topics: geology, mineralogy