O’danielite

Odanielit

H₂Na(Zn, Mg)₃(AsO₄)₃

monoclinic

Obertiite

Obertiit

NaNa₂[Mg₃Fe³⁺Ti⁴⁺]Si₈O₂₂O₂

monoclinic

Oboyerite

Oboyerit

Pb₆H₆(Te⁴⁺O₃)₃(Te⁶⁺O₆)₂ • 2H₂O

triclinic

Obradovicite

Obradovicit

H₄(K, Na)CuFe³⁺₂(AsO₄)(MoO₄)₅ • 12H₂O

orthorhombic

Odinite

Odinit

(Fe³⁺, Mg, Al, Fe²⁺)_2.5(Si, Al)₂O₅(OH)₄

monoclinic or hexagonal

Odintsovite

Ogyincovit

K₂Na₄Ca₃Ti₂Be₄Si₁₂O₃₈

orthorhombic

Oenite

Oenit

CoSbAs

orthorhombic

Offretite

Offretit

CaKMgAl₅Si₁₃O₃₆ • 16H₂O

hexagonal

Oftedalite

Oftedalit

(Sc, Ca, Mn²⁺)₂K(Be, Al)₃Si₁₂O₃₀

hexagonal

Ogdensburgite

Ogdensburgit

Ca₂(Zn, Mn²⁺)Fe³⁺₄(AsO₄)₄(OH)₆ • 6H₂O

orthorhombic

Ohmilite

Ohmilit

Sr₃(Ti, Fe³⁺)(Si₂O₆)₂(O, OH) • 2-3H₂O

monoclinic

Ojuelaite

Ojuelait

ZnFe³⁺₂(AsO₄)₂(OH)₂ • 4H₂O

monoclinic

Okanoganite-(Y)

Okanoganit-(Y)

(Na, Ca)₃(Y, Ce)₁₂B₂Si₆O₂₇F₁₄

trigonal

Okenite

Okenit

Ca₅Si₉O₂₃ • 9H₂O

triclinic

Okhotskite

Ohotszkit

Ca₂(Mn²⁺, Mg)(Mn³⁺, Al, Fe³⁺)₂Si₃O₁₀ (OH)₄

monoclinic (?)

Oldhamite

Oldhamit

(Ca, Mg)S

cubic

Olekminskite

Olekminszkit

Sr(Sr, Ca, Ba)(CO₃)₂

trigonal

Olenite

Olenit

NaAl₃Al₆(BO₃)₃Si₆O₁₈O₃(OH)

trigonal

Olgite

Olgit

Na(Sr, Ba)PO₄

trigonal

Olivenite

Olivenit

Cu₂(AsO₄)(OH)

monoclinic

Olkhonskite

Olhonszkit

(Cr, V)₂Ti₃O₉

monoclinic

Olmsteadite

Olmsteadit

KFe²⁺₂(Nb, Ta)O₂(PO₄)₂ • 2H₂O

orthorhombic

Olsacherite

Olsacherit

Pb₂(SeO₄)(SO₄)

orthorhombic

Olshanskyite

Olsanszkiit

Ca₃B₄(OH)₁₈

monoclinic (?)

Olympite

Olimpit

LiNa₅(PO₄)₂

orthorhombic

Omeiite

Omeiit

(Os, Ru)As₂

orthorhombic

Ominelite

Ominelit

(Fe, Mg)Al₃BSiO₉

orthorhombic

Omphacite

Omfacit

(Ca, Na)(Mg, Fe, Al)Si₂O₆

monoclinic

Oneillite

Oneillit

Na₁₅Ca₃Mn₃Fe₃Zr₃NbSi₂₅O₇₃(O, OH, H₂O)₃(OH, Cl)₂

trigonal

Onoratoite

Onoratoit

Sb₈O₁₁Cl₂

triclinic

Oosterboschite

Oosterboschit

(Pd, Cu)₇Se₅

orthorhombic

Opal

Opál

SiO₂ • nH₂O

amorphous

Orcélite

Orcélit

Ni_5-xAs₂ (x = 0.23)

hexagonal

Ordoñezite

Ordoñezit

ZnSb⁵⁺₂O₆

tetragonal

Örebroite

Örebroit

Mn²⁺₃(Sb⁵⁺, Fe³⁺)(SiO₄)(O, OH)₃

trigonal

Oregonite

Oregonit

Ni₂FeAs₂

hexagonal

Organovaite-Mn

Organovait-Mn

K₈Mn₄Nb₁₆(Si₄O₁₂)₈O₁₆ • nH₂O

monoclinic

Organovaite-Zn

Organovait-Zn

K₈Zn₄Nb₁₆(Si₄O₁₂)₈O₁₆ • nH₂O

monoclinic

Orickite

Orickit

2CuFeS₂ • H₂O

hexagonal

Orientite

Orientit

Ca₂Mn²⁺Mn³⁺₂Si₃O₁₀(OH)₄

orthorhombic

Orlandiite

Orlandiit

Pb₃Cl₄(SeO₃) • H₂O

triclinic

Orlymanite

Orlymanit

Ca₄Mn²⁺₃Si₈O₂₀(OH)₆ • 2H₂O

trigonal

Orpheite

Orpheit

H₆Pb₁₀Al₂₀(PO₄)₁₂(SO₄)₅(OH)₄₀ • 11H₂O (?)

trigonal

Orpiment

Auripigment

As₂S₃

monoclinic

Orschallite

Orschallit

Ca₃(SO₃)₂(SO₄) • 12H₂O

trigonal

Orthobrannerite

Ortobrannerit

U⁴⁺U⁶⁺Ti₄O₁₂(OH)₂

orthorhombic

Orthochamosite

Ortochamosit

(Fe²⁺, Mg, Fe³⁺)₅Al(Si₃Al)O₁₀(OH, O)₈

orthorhombic

Orthochrysotile

Ortokrizotil

Mg₃Si₂O₅(OH)₄

orthorhombic

Orthoclase

Ortoklász

KAlSi₃O₈

monoclinic

Orthoericssonite

Ortoericssonit

BaMn²⁺₂Fe³⁺OSi₂O₇(OH)

orthorhombic

Orthojoaquinite-(Ce)

Ortojoaquinit-(Ce)

Ba₂NaCe₂Fe²⁺Ti₂Si₈O₂₆(OH, F) • H₂O

orthorhombic

Orthojoaquinite-(La)

Ortojoaquinit-(La)

Ba₂NaLa₂Fe²⁺Ti₂Si₈O₂₆(OH, F) • H₂O

orthorhombic

Orthominasragrite

Ortominasragrit

V⁴⁺O(SO₄)(H₂O)₅

orthorhombic

Orthopinakolite

Ortopinakolit

(Mg, Mn²⁺)₂Mn³⁺BO₅

orthorhombic

Orthoserpierite

Ortoserpierit

Ca(Cu²⁺, Zn)₄(SO₄)₂(OH)₆ • 3H₂O

orthorhombic

Orthowalpurgite

Ortowalpurgin

Bi₄(UO₂)O₄(AsO₄)₂ • 2H₂O

orthorhombic

Osarizawaite

Osarizawait

PbCu²⁺Al₂(SO₄)₂(OH)₆

trigonal

Osarsite

Ozarzit

(Os, Ru)AsS

monoclinic

Osbornite

Osbornit

TiN

cubic

Osmiridium

Ozmirídium

(Ir, Os)

cubic

Osmium

Ozmium

Os

hexagonal

Osumilite

Osumilit

(K, Na)(Fe²⁺, Mg)₂(Al, Fe³⁺)₃(Si, Al)₁₂ O₃₀

hexagonal

Osumilite-(Mg)

Osumilit-(Mg)

(K, Na)(Mg, Fe²⁺)₂(Al, Fe³⁺)₃(Si, Al)₁₂ O₃₀

hexagonal

Oswaldpeetersite

Oswaldpeetersit

(UO₂)₂(CO₃)(OH)₂ • 4H₂O

monoclinic

Otavite

Otavit

CdCO₃

trigonal

Otjisumeite

Otjisumeit

PbGe₄O₉

triclinic

Ottemannite

Ottemannit

Sn₂S₃

orthorhombic

Ottrélite

Ottrélit

(Mn²⁺, Fe²⁺, Mg)₂Al₄Si₂O₁₀(OH)₄

monoclinic or triclinic

Otwayite

Otwayit

Ni₂(CO₃)(OH)₂ • H₂O

orthorhombic

Oulankaite

Oulankait

(Pd, Pt)₅(Cu, Fe)₄SnTe₂S₂

tetragonal

Ourayite

Ourayit

Ag₃Pb₄Bi₅S₁₃

orthorhombic

Oursinite

Oursinit

(Co, Mg)(UO₂)₂Si₂O₇ • 6H₂O

orthorhombic

Ovamboite

Ovamboit

Cu₂₀(Fe, Cu, Zn)₆W₂Ge₆S₃₂

cubic

Overite

Overit

CaMgAl(PO₄)₂(OH) • 4H₂O

orthorhombic

Owensite

Owensit

(Ba, Pb)₆(Cu, Fe, Ni)₂₅S₂₇

cubic

Owyheeite

Owyheeit

Pb_10-2xAg_3+xSb_11+xS₂₈ (x = -0.13-0.20)

orthorhombic

Oxammite

Oxammit

(NH₄)₂C₂O₄ • H₂O

orthorhombic

Oxykinoshitalite

Oxikinoshitalit

Ba(Mg₂Ti)(Si₂Al₂)O₁₀O₂

monoclinic

Oyelite

Oyelit

Ca₁₀B₂Si₈O₂₉ • 12.5H₂O

orthorhombic