's Image Gallery

Olivenite: Cu2AsO4(OH)  
Arsenogoyazite: (Sr,Ca,Ba)Al3(AsO4,PO4)2(OH,F)5·(H2O)

Comments: White micro-botryoids of arsenogoyazite with light green acicular crystal sprays of olivenite and dark green malachite on brown limonite.
Location: Centennial Eureka Mine, Juab County, Utah. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Olivine: (Mg,Fe)2SiO4  
Forsterite: Mg2SiO4

Comments: Peridot (Forsterite) recrystallized at the base.
Location: Skardu, Nooristan, Pakistan. Scale: 2.5 x 2.7 cm.
© Fabre Minerals

Olmiite: CaMn[SiO3(OH)](OH)

Comments: Spherical aggregate of prismatic crystals of pinkish tan olmiite..
Location: N'chwaning II Mine, section 5 south stope, 46-47 roof, Kuruman South Africa. Scale: Specimen size 2.5 × 2 × 1.4 cm.
© Fabre Minerals

Olmsteadite: KFe++2(Nb,Ta)(PO4)2O2·2(H2O)

Comments: Dark brown crystals of olmsteadite with jahnsite on siderite.
Location: Big Chief mine, Keystone, Penningtion County, South Dakota, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Olsacherite: Pb2(SeO4)(SO4)

Comments: Light yellow crystals of olsacherite up to 2 mm in matrix.
Location: Colquechaca, Potosí, Bolivia. Scale: Picture size 1.5 cm.
© John Veevaert

Olshanskyite: Ca2[B3O3(OH)6]OH·3(H2O)  
Henmilite: Ca2Cu[B(OH)4]2(OH)4

Comments: Milky white olshanskyite hosting crystals of deep blue henmilite to 6 mm across.
Location: Fuka Mine, Bicchu Town, Kawakama Co., Okayama Pref., Japan. Scale: Crystal size 6 mm.
© John Veevaert

Ominelite: (Fe++,Mg)Al3BSiO9

Comments: Photomicrograph of thin-section (plain light) of zoned ominelite (omn) with quartz (qtz) and plagioclase (pl) in alkali feldspar. (AmMin 87:163).
Location: Misen River in Tenkawa, Yoshino, Nara Prefecture, Japan. Scale: Grain size 0.6 mm.
© American Mineralogist

Omphacite: (Ca,Na)(Mg,Fe++,Al)Si2O6

Comments: Dark green crystalline omphacite with glaucophane.
Location: Healdsburg, Sonoma County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Oneillite: Na15Ca3Mn3Fe++3Zr3Nb(Si25O73)(O,OH,H2O)3(OH,Cl)2

Comments: Brownish-yellow grains of oneillite in white K-feldspar from the type locality.
Location: Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire, Rouville, Montérégie, Québec, Canada. Scale: FOV is 6x5 mm.
© Pavel M. Kartashov

Onoratoite: Sb8O11Cl2

Comments: White crystals of onoratoite with a yellow crystal of sulphur.
Location: Cetine di Cotorniano Mine (Cetine Mine; Tafone Mine), Rosia, Siena, Tuscany, Italy. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Oosterboschite: (Pd,Cu)7Se3

Comments: Polished section showing oosterboschite (metallic yellow) and its alteration product (light brown) as intergranular veinlets surrounding mineralized malachite and quartz (dark grey), and several grains of goethite (light grey).
Location: Copper Hills in the East Pilbara region of Western Australia. (CanMin, v 40:419). Scale: Picture Size 0.56 mm.
© Canadian Mineralogist

Opal: SiO2·n(H2O)

Comments: Colorful white opal on a sandstone matrix.
Location: Queensland, Australia. Scale: 9 x 6 x 3 cm.
© Isaias Casanova / IC Minerals

Opal: SiO2·n(H2O)

Comments: Section of fossilized tree limb that is now completely replaced by black opal.
Location: Virgin Valley District, Humboldt Co., Nevada, USA. Scale: 20x13x11 mm.
© John Betts - Fine Minerals

Opal: SiO2·n(H2O)  
Todorokite: (Na,Ca,K)2(Mn++++,Mn+++)6O12·3-4.5(H2O)

Comments: Dendritic todorokite in white opal.
Location: Brosso Mine, Ivrea, Torino, Piemonte, Italy. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Orcelite: Ni5-xAs2 (x=0.23)

Comments: Bronze micro spherical orcelite coated with greenish zaratite.
Location: Tiebaghi Massif, New Caledonia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ordonezite: ZnSb2O6

Comments: Greenish, glassy crystals of ordonezite.
Location: Santin mine, Guanajuato, Mexico. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Oregonite: Ni2FeAs2

Comments: Steel gray, altering to brown, rounded oregonite pebble with serpentinite rock.
Location: Josephine Creek, Josephine County, Oregon, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Organovaite-Mn: K2Mn(Nb,Ti)4(Si4O12)2(O,OH)4·6(H2O)

Comments: Crude pink organovaite-Mn pseudomorphs after vuonnemite.
Location: Mt. Karnasurt, Lovozero, Kola Peninsula, Russia. Scale: Specimen Size 1.5x2.5 cm.
© Diederik Visser

Organovaite-Zn: K2Zn(Nb,Ti)4(Si4O12)2(O,OH)4·6(H2O)

Comments: Crude pinkish-brown organovaite-Zn crystals in matrix.
Location: Mt. Karnasurt, Lovozero, Kola Peninsula, Russia. Scale: Specimen Size 1x2.5 cm.
© Diederik Visser

Orickite: CuFeS2·(H2O)

Comments: Black and white image of a polished section showing intergrown crystals of orickite in sodalite (dark). (AmMin 68:246).
Location: Mafic alkalic diatreme at Coyote Peak near Orick, Humboldt County, California, USA. Scale: Image size 0.44 mm.
© American Mineralogist