Uchucchacuaite

Comments: Corroded grain of uchucchacuaite in matrix.
Location: Bera Basin #4 mine, King Co., Washington, USA. Scale: Crystal size 1 mm.
© Tom Loomis / Dakota Matrix

Uhligite

Comments: Black granular uhligite in syenite rock.
Location: near Lake Magadi, Rift Valley Province, Kenya. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uklonskovite

Comments: Minute crystals and crystalline uklonskovite.
Location: Pampa del Pique III, Antofagasta, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ulexite

Comments: Tray of fibrous Ulexite fragments which have been cut and polished perpendicular to the fibers. This shows the fiber-optic "TV stone" effect which transmit images through the fragments.
Location: U.S. Borax Mine, Boron, Kramer District, Kern County, California, USA. Scale: Picture size 10 cm.
© Dave Barthelmy

Ulrichite

Comments: Green ulrichite microcrystal tuft on quartz.
Location: Lake Boga, Victoria, Australia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ulrichite

Comments: Green, acicular crystals of ulrichite on matrix. Co-type specimen (?) collected by the discoverer, Anthony Fraser.
Location: Lake Boga granite quarry, Lake Boga, Victoria, Australia. Scale: Picture size 2 mm.
© Paul M. Schumacher

Ulvospinel

Comments: Black sub-metallic massive ulv?spinel.
Location: Otanmaki, Sout, Oulu, Finland. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Umangite   Athabascaite   Berzelianite

Comments: Reflected light photomicrograph of umangite (pinkish), berzelianite (gray), athabascaite (small white areas in berzelianite), calcite (olive).
Location: Sierra de Umango, La Rioja, Argentin. Scale: Not Given.
© Jeff Weissman / Photographic Guide to Mineral Species

Umangite   Bellidoite   Berzelianite

Comments: Dark bellidoite inclusions in black berzelianite with white umangite.
Location: Habri, near Tisnov, Jihomoravsky, Czech Republi. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Umangite   Tyrrellite

Comments: Bright metallic partial cubic tyrrellite crystal in altering umangite.
Location: Eagle Claims, near Hal Lake, Beaverlodge, Saskatchewan, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Umangite   Berzelianite

Comments: Black massive umangite intergrown with dark blue metallic berzelianite.
Location: Borsov, Bohemia, Vychodocesky, Czech Republic. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Umbozerite

Comments: Dark brown prismatic umbozerite masses in pegmatite rock.
Location: Pegmatite #100, Mount Karnasurt,  Lovozero Massif, Kola Peninsula, Murmansk District,. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Umohoite

Comments: Orange Umohoite aggregates on matrix.
Location: Rab?jac, Lod?ve, H?rault, Languedoc-Roussillon, France. Scale: Picture size 1 mm.
© Thomas Witzke / Abraxas-Verlag

Ungarettiite

Comments: Dark red ungarettiite veinlets in rock.
Location: Hoskins Mine, near Grenfell, New South Wales, Australia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ungemachite   Metasideronatrite

Comments: Translucent rounded ungemachite microcrystal on yellow metasideronatrite.
Location: Chuquicamata, Antofagasta, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uralolite

Comments: Radiating aggregates of uralolite.
Location: Brandr?cken, Weinebene pass, Koralpe Mts, Carinthia, Austria. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Uramphite

Comments: Thin encrustions of urampite on a fracture surface in sub-bituminous coal.
Location: Tura-Kavak, Issyk-Kul'skaya Oblast', Kyrgyzstan. Scale: See Image.
© Paul M. Schumacher

Urancalcarite

Comments: Bright yellow earthy spots composed of micro acicular urancalcarite crystals associated with rusty browm huemulite.
Location: Huemul mine, Malargue, Mendoza, Argentina. Scale: Picture size 1.5 cm.
© Tom Loomis / Dakota Matrix

Uraninite   Uranophane

Comments: Sharp, cubic crystals of black uraninite on yellow uranophane.
Location: Teofilo Otoni, Minas Gerais, Brazil. Scale: Picture size 1.5 mm.
© Paul M. Schumacher

Uraninite

Comments: Polished slab of black "gummite" ore with the uraninite altering to various secondary uranium minerals in a brecciated matrix.
Location: Ruggles mine, Graton, New Hampshire, USA. Scale: Specimen size 11.4 cm.
© Paul M. Schumacher

Uraninite

Comments: Black uraninite impregnating coaly wood fragments. You can see the woody structure in detail preserved in the uraninite.
Location: Grants mineral district, Westwater Canyon Member of the Morrison Formation.. Scale: Picture size 5 mm.
© Paul M. Schumacher

Uranocircite   Meta-uranocircite

Comments: Brilliant, fluorescent yellow green crystals of uranocircite altered to meta-uranocircite.
Location: Bergen, Vogtland, Saxony, Germany. Scale: 2.3 x 2.2 cm.
© John Veevaert

Uranocircite   Phosphuranylite

Comments: Yellow, waxy phosphuranylite with green uranocircite in matrix.
Location: Bergen, Falkenstein, Vogtland, Saxony, Germany. Scale: Picture size 0.5 cm.
© Paul M. Schumacher

Uranocircite   Meta-uranocircite

Comments: Crystal fragment of uranocircite fracturing due to dehydration to meta-uranocircite. The most common are 100 and 010 fractures, with 110 close behind. But notice the 210 and 410 fractures (breaks) as well.
Location: . Scale: Crystal size 2x3.5 cm.
© Paul M. Schumacher

Uranocircite

Comments: Yellowish green square, foliated uranocircite crystal.
Location: Bergen, Falkenstein, Vogtland, Saxony, Germany. Scale: Crystal size 1.3 cm.
© Tom Loomis / Dakota Matrix

Uranophane

Comments: Bright yellow crystals of uranophane with black uraninite.
Location: Teofilo Otoni, Minas Gerais, Brazil. Scale: Picture size 3.5 mm.
© Paul M. Schumacher

Uranophane   Uraninite

Comments: Sharp, cubic crystals of black uraninite on yellow uranophane.
Location: Teofilo Otoni, Minas Gerais, Brazil. Scale: Picture size 1.5 mm.
© Paul M. Schumacher

Uranophane

Comments: Yellow uranophane acicular crystal tufts.
Location: Faraday Mine, Bancroft, Ontario, Canada. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uranophane-beta

Comments: Bright yellow uranophane-beta crystalline aggregates.
Location: Rossing mine, Rossing, Namibia. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Uranopilite   Zippeite

Comments: Bright yellow uranopilite and reddish brown zippeite encrustations on uranium ore.
Location: Happy Jack Mine, White Canyon, Utah. Scale: 3 cm.
© John Veevaert

Uranopilite

Comments: Bright yellow crystalline uranopilite aggregate of prismatic microcrystals.
Location: Jachymov, Northwestern Bohemia, Zapadocesky, Czech Republic. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uranopilite   Johannite

Comments: Bright yellow rosettes of uranopilite with pale greenish yellow johannite on matrix.
Location: Apex Mine, Lander Co., Nevada, USA. Scale: Picture size 0.5 cm.
© Paul M. Schumacher

Uranopilite   Johannite

Comments: Green aggregates of minute, acicular johannite and yellow uranopilite and clear, tabular aragonite crystals on matrix.
Location: Apex Mine, Lander Co., Nevada, USA. Scale: Picture size 1.5 cm.
© Paul M. Schumacher

Uranopolycrase

Comments: Brownish-black uranopolycrase microcrystals on quartz.
Location: Fonte del Prete, near San Piero in Campo, Elba, Tuscany, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uranopolycrase

Comments: Brown to black, paper thin, elongated uranopolycrase crystals to 1mm.
Location: Cavetta Bassa, Elba Isle, Livorno Province, Tuscany, Italy. Scale: Picture size 2 mm.
© Tom Loomis / Dakota Matrix

Uranospathite

Comments: Minute, less than 0.1cm platy yellow crystals or uranospahtite on matrix.
Location: Pedro Alvaro, Salamanca, Spain. Scale: Picture size 1 cm.
© Tom Loomis / Dakota Matrix

Uranosphaerite

Comments: Yellow-orange earthy uranosphaerite crusts.
Location: Kersegalec en Lignol, Vendee, France. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uranospinite

Comments: Translucent platy uranospinite microcrystals on matrix.
Location: Grube Buhlskopf, near Ellweiler, Rheinland-Pfalz, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uranpyrochlore   Samarskite-(Y)

Comments: Deep greenish-brown resinous crystalline massive uranpyrochlore with black samarskite-(Y).
Location: Beryl Hill, near Yinnietharra Station, Western Australia, Australia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uricite

Comments: White powdery uricite aggregate.
Location: Dingo Donga Cave, near Rawlinna, Western Australia, Australia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Urusovite

Comments: Green urusovite grain.
Location: Northern Breakthrough, Great Fissure (Main Fracture) eruption, Tolbachik volcano, Kamchatka Oblast', Far-Eastern Region, Russia. Scale: Crystal length 0.7 mm.
© Thomas Witzke / Abraxas-Verlag

Ushkovite   Roscherite

Comments: Translucent ushkovite microcrystals with orange roscherite on feldspar.
Location: Galileia, Minas Gerais, Brazil. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ussingite   Cuprostibite

Comments: Massive ussingite hosting grains of the very rare copper antimony-thallium bearing cuprostibite.
Location: Ilimaussaq, Tasseq, Greenland. Scale: 4.8 x3.4 cm.
© John Veevaert

Ussingite   Vuonnemite

Comments: Massive, violet colored ussingite with a single bladed partial crystal of white vuonnemite 1.5 cm in length.
Location: Mt. Karnasurf, Lovozero, Russia. Scale: 4.2 x 3 cm.
© John Veevaert

Ussingite   Gerasimovskite

Comments: Pale tan gerasimovskite pseudomorphous after epistolite crystal, in purple ussingite.
Location: Lovozero Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Utahite

Comments: Blue utahite grain in matrix.
Location: Centennial Eureka Mine, Tintic District (East Tintic Mountains), Juab Co., Utah, USA. Scale: Picture size 1 mm.
© Thomas Witzke / Abraxas-Verlag

Uvanite

Comments: Yellowish brown uvanite coating on sandstone.
Location: Temple Rock, Emery County, Utah, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Uvarovite

Comments: Green uvarovite (garnet) crystal group.
Location: Mokkivaara mine, Outokumpu, Finland. Scale: 1.3x1.2x1 cm.
© Fabre Minerals

Uvite

Comments: Reddish brown, prismatic uvite crystals.
Location: Brumado, Bahia, Brazil. Scale: 4.5 x 5.5 cm.
© Fabre Minerals

Uytenbogaardtite

Comments: Gray crystal grains of uytenbogaardtite to 1mm throughout matrix with electrum.
Location: Bullfrog mine, Nye County, Nevada, USA. Scale: Slab 1cm thick 6x6cm.
© Tom Loomis / Dakota Matrix

Uzonite

Comments: Yellow powdery uzonite encrustation.
Location: Uzon Volcano, Kamchatka District, Russian Far East, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species