ominelite
An orthorhombic-dipyramidal blue mineral containing aluminum, boron, iron, magnesium, oxygen, and silicon.

oncolite
a spherical sedimentary structure formed by cyanobacteria

oncolith
Synonym of oncolite.

onegite
A form of amethyst having hair-like inclusions of goethite

oneillite
A trigonal-pyramidal yellowish brown mineral containing calcium, chlorine, hydrogen, iron, manganese, niobium, oxygen, silicon, sodium, and zirconium.

onkilonite
A nepheline basalt mineral.

onoratoite
A monoclinic-prismatic white mineral containing antimony, chlorine, and oxygen.

oolite
A rock consisting of spherical grains within a mineral cortex accreted around a nucleus, often of quartz grains.
An ooid or oolith.

oolites
plural of oolite

oosterboschite
An orthorhombic black mineral containing copper, palladium, and selenium.

opalines
plural of opaline

opalite
Opal; some variety of it; an artificial mineral resembling it.
Opal glass, formed into tiles or bricks.

opdalite
A charnockitic form of granodiorite

opdalites
plural of opdalite

ophicalcite
ophite; verd antique

ophthalmite
An eyestalk.
A migmatite that is characterized by the presence of concentric or lenticular aggregates of newly formed minerals that reflect post-anatectic processes.

ophthalmites
plural of ophthalmite

orangeite
A kind of kimberlite with phlogopite macrocrysts and microphenocrysts.

orangeites
plural of orangeite

orangite
An orange-yellow variety of thorite, found in Norway.

orangites
plural of orangite

orbicule
An inclusion in an igneous rock
A lipid droplet, covered by sporopollenin, in the anthers of some plants

orbicules
plural of orbicule

orbuculum
A crystal ball.

orbuculums
plural of orbuculum

orcelite
A hexagonal-dihexagonal pyramidal orange white mineral containing arsenic and nickel.

ordanchite
A variety of trachyandesite.

ordanchites
plural of ordanchite

ordonezite
A tetragonal pyramidal mineral found in rhyolite fractures.

orebodies
plural of orebody

orebody
a mass or region of ore

oregonite
A hexagonal nickel iron arsenide mineral.

organobentonite
A bentonite that has been organically modified.

orickite
A hexagonal brass yellow mineral containing copper, hydrogen, iron, oxygen, and sulfur.

orientite
An orthorhombic-dipyramidal mineral containing calcium, hydrogen, manganese, oxygen, and silicon.

orlandiite
A triclinic-pinacoidal mineral containing chlorine, hydrogen, lead, oxygen, and selenium.

orlymanite
A trigonal dark brown mineral containing calcium, hydrogen, manganese, oxygen, and silicon.

ornithogeography
The study of the geological distribution of birds.

orpheite
A trigonal-hexagonal scalenohedral mineral containing aluminum, hydrogen, lead, oxygen, phosphorus, and sulfur.

orschallite
A trigonal-hexagonal scalenohedral colorless mineral containing calcium, hydrogen, oxygen, and sulfur.

orthid
A brachiopod shell of the genus †Orthis (or allied genera) in the family †Orthidae.
A mineral soil with ochric epipedon that does not have an argillic or natric horizon.

orthide
Alternative form of orthid.

orthides
plural of orthide

orthids
plural of orthid

orthite
A variety of allanite occurring in slender prismatic crystals

orthites
plural of orthite

orthobrannerite
An orthorhombic-disphenoidal mineral containing hydrogen, oxygen, titanium, and uranium.

orthochamosite
An orthorhombic mineral containing aluminum, hydrogen, iron, magnesium, oxygen, and silicon.

orthochrysotile
An orthorhombic polytype of chrysotile.

orthochrysotiles
plural of orthochrysotile

orthodome
A dome that is parallel to the orthodiagonal in a monoclinic crystal.

orthodomes
plural of orthodome

orthoericssonite
An orthorhombic-dipyramidal reddish black mineral containing barium, hydrogen, iron, manganese, oxygen, and silicon.

orthofelsite
Synonym of orthophyre.

orthogneiss
A gneiss derived from an igneous rock.

orthogneisses
plural of orthogneiss

orthominasragrite
An orthorhombic-pyramidal mineral containing hydrogen, oxygen, sulfur, and vanadium.

orthophyre
a porphyritic rock that contains phenocrysts of orthoclase embedded in feldspar

orthophyres
plural of orthophyre

orthopinakiolite
An orthorhombic-dipyramidal black mineral containing boron, iron, magnesium, manganese, and oxygen.

orthoquartzite
A very pure quartz sandstone composed of usually well rounded quartz grains cemented by silica.

orthoquartzites
plural of orthoquartzite

orthoserpierite
An orthorhombic-pyramidal pale blue green mineral containing calcium, copper, hydrogen, oxygen, sulfur, and zinc.

orthowalpurgite
An orthorhombic-dipyramidal pale yellow mineral containing arsenic, bismuth, hydrogen, oxygen, and uranium.

oryctognosy
Knowledge about things dug up, especially what is now considered mineralogy.

osarsite
A monoclinic-prismatic gray mineral containing arsenic, osmium, ruthenium, and sulfur.

osbornite
A golden yellow mineral containing nitrogen and titanium.

osmiridium
A hard, corrosion-resistant alloy of osmium and iridium, used in pen nibs.

osmiridiums
plural of osmiridium

osumilite
A hexagonal mineral with the chemical formula (K,Na)(Mg,Fe⁺²)₂(Al,Fe)₃(Si,Al)₁₂O₃₀·H₂O.

osumilites
plural of osumilite

oswaldpeetersite
A monoclinic-prismatic canary yellow mineral containing carbon, hydrogen, oxygen, and uranium.

otjisumeite
A triclinic mineral containing germanium, lead, and oxygen.

ottemannite
An orthorhombic-dipyramidal reddish gray mineral containing sulfur and tin.

ottrelite
A form of the mineral chloritoid.

ottrelites
plural of ottrelite

ouachitite
An ultramafic variety of damkjernite.

ouachitites
plural of ouachitite

ouklip
hardpan (soil layer mostly impervious to water)

ourayite
An orthorhombic-dipyramidal gray mineral containing bismuth, lead, silver, and sulfur.

oursinite
An orthorhombic pale yellow mineral containing cobalt, hydrogen, magnesium, oxygen, silicon, and uranium.

ouvarovite
Archaic form of uvarovite.

ovamboite
An isometric-hextetrahedral gray mineral containing arsenic, copper, gallium, germanium, iron, molybdenum, sulfur, tin, tungsten, vanadium, and zinc.

overburden
To overload or overtax.

overburdens
plural of overburden

overburthen
Archaic form of overburden.

overite
A form of segelerite in which the iron is replaced by aluminium.

overlayer
A layer of adatoms adsorbed onto a surface, as onto the surface of a single crystal.

overlayers
plural of overlayer

owensite
An isometric-hexoctahedral black mineral containing barium, copper, iron, lead, nickel, and sulfur.

owyheeite
An orthorhombic-dipyramidal gray-white mineral containing antimony, bismuth, lead, silver, and sulfur.

oxalite
A yellow mineral, one of the oxalates of iron.

oxalites
plural of oxalite

oxammite
An orthorhombic-disphenoidal mineral containing carbon, hydrogen, nitrogen, and oxygen.

oxhaverite
Synonym of apophyllite.

oxyapatite
Synonym of fluorapatite.

oxykinoshitalite
A monoclinic mineral containing aluminium, barium, magnesium, oxygen, silicon and titanium.

oyelite
An orthorhombic white mineral containing boron, calcium, hydrogen, oxygen, and silicon.

ozocerite
A dark waxy mineral, found associated with petroleum in some sandstones, used to make polishes.

ozocerites
plural of ozocerite

ozokerit
Archaic form of ozocerite.

ozokerite
Alternative form of ozocerite.

ozokerites
plural of ozokerite

ozokerits
plural of ozokerit

paarite
An orthorhombic-dipyramidal tin white mineral containing bismuth, copper, iron, lead, and sulfur.

pabstite
A hexagonal-ditrigonal dipyramidal mineral containing barium, oxygen, silicon, tin, and titanium.

paceite
A tetragonal-dipyramidal dark blue mineral containing calcium, carbon, copper, hydrogen, and oxygen.

pachnolite
A monoclinic-prismatic mineral containing aluminum, calcium, fluorine, hydrogen, oxygen, and sodium.

paderaite
A monoclinic-prismatic creamy white mineral containing bismuth, copper, lead, silver, sulfur, and tellurium.