Mineral Specimen Images (O)

Obertiite: NaNa2(Mg3Fe+++Ti)Si8O22(O,F,OH)2

Comments: Pinkish grains of obertiite in matrix.
Location: Bellerberg Mt., Eifel District, Rheinland-Phalz, Germany. Scale: Specimen Size 7x6 mm.
© Sergey Vasiliev / Systematic Mineralogy

Obradovicite: H4(K,Na)Cu++Fe+++2(AsO4)(MoO4)5·12(H2O)

Comments: Brownish yellow obradovicite coatings on quartz.
Location: Chuquicamata, Antofagasta, Chile. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Offretite: (K2,Ca,Mg)2.5Al5Si13O36·15(H2O)

Comments: Clear crystal of offretite on matrix.
Location: Mont Simiouse, near Montbrison, Loire, France. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Ogdensburgite: Ca2(Zn,Mn)Fe+++4(AsO4)4(OH)6·6(H2O)

Comments: Reddish-brown, massive ogdensburgite.
Location: Ogdensburg, Franklin Mining District, Sussex Co., New Jersey, USA. Scale: Picture size 6 mm.
© Thomas Witzke / Abraxas-Verlag

Ohmilite: Sr3(Ti,Fe+++)(Si2O6)2(O,OH)·2-3(H2O)

Comments: Pale yellow translucent acicular ohmilite crystal cluster in matrix.
Location: Hashidate, Ohmi cho, Niigata, Japan. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ojuelaite: ZnFe+++2(AsO4)2(OH)2·4(H2O)

Comments: Yellow-green ojuelaite masses on limonite and quartz.
Location: Mina Ojuela, Mapimi, Durango, Mexico. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Okanoganite-(Y): (Na,Ca)3(Y,Ce)12Si6B2O27F14

Comments: Cream-colored twinned crystal of okanoganite-(Y) on matrix.
Location: Washington Pass, Okanogan County, Washington, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Okayamalite: Ca2B2SiO7

Comments: Intergrowth between crystalline okayamalite (a) and amorphous silica (b). Okayamalite here forms regular lamellae elongated along [001], typically 400 Å thick. The grainy area (c) corresponds to the graphite film..
Location: Skarn sample from the Arendal district, Sorlandet, Norway. (AmMin, v85:1508). Scale: See Image.
© American Mineralogist

Okenite: Ca3[Si6O15]·6(H2O)

Comments: Cotton-ball cluster of white okenite crystals.
Location: Khandivali quarry, Maharashtra, India. Scale: 3x3x2 cm.
© John Betts - Fine Minerals

Oldhamite: (Ca,Mg,Fe)S

Comments: Brown crystalline oldhamite grains in anhydrite.
Location: Ronneburg, Thuringen, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Olenite: NaAl3Al6(BO3)3(Si6O18)(O,OH)4

Comments: Colorless, boron-rich crystal of Olenite in quartz.
Location: Koralpe, Styria, Austria. Scale: Crystal size 3 cm.
© Andreas Ertl / Institut für Mineralogie und Kristallographie

Olgite: Na(Sr,Ba)PO4

Comments: Green mm-sized olgite crystals in matrix.
Location: Kedykverpakhk Mt., Lovozero, Kola, Russia. Scale: Not Given.
© Sergey Vasiliev / Systematic Mineralogy

Oligoclase: (Na,Ca)(Si,Al)4O8  
Plagioclase: (Na,Ca)(Si,Al)4O8

Comments: Rectangular cleavage fragment of salmon-orange oligoclase (sunstone) feldspar.
Location: Norway. Scale: 47x30x7 mm.
© John Betts - Fine Minerals

Oligoclase: (Na,Ca)(Si,Al)4O8  
Plagioclase: (Na,Ca)(Si,Al)4O8

Comments: Clear glassy crystalline oligoclase with milky quartz and muscovite.
Location: Bakersville, Mitchell County, North Carolina, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Olivenite: Cu2AsO4(OH)

Comments: Dark green crystals of olivenite on matrix.
Location: Majuba Hill mine, Pershing County, Nevada, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

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