opal
A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.
A mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.
The colour of opal: any shade of blue with bright flecks of other colours, such as white, yellow, and red.
A colloquial name used in molecular biology referring to a particular stop codon sequence, "UGA."
Any of various lycaenid butterflies of the genus Nesolycaena.

opals
plural of opal

organomontmorillonite
Alternative form of organo-montmorillonite.

orthoclase
Potassium aluminum silicate, KAlSi₃O₈, a common feldspar of igneous, plutonic, and metamorphic rocks. Orthoclase is the main feldspar of pegmatite occurrences, where it is most commonly flesh-colored. Orthoclase is used in the ceramic and glass industries and as a decorative gravel.

orthoclases
plural of orthoclase

orthoferrosilite
An iron silicate that crystallizes as an orthorhombic pyroxene

orthoferrosilites
plural of orthoferrosilite

orthopyroxene
Any pyroxene that forms orthorhombic crystals.

orthopyroxenes
plural of orthopyroxene

orthopyroxine
Misspelling of orthopyroxene.

orthosilicate
Any salt or ester of orthosilicic acid, (M⁺)₄SiO₄⁴⁻ or Si(OR)₄.
Any silicate mineral, such as garnet or olivine, in which the SiO₄ tetrahedra do not share oxygen atoms with each other.

orthosilicates
plural of orthosilicate

osarizawaite
A greenish-yellow mineral with the chemical formula PbCuAl₂(SO₄)₂(OH)₆, having rhombohedral crystals.

oscarkempffite
A rare opaque mineral found in Bolivia with the chemical formula Ag₁₀Pb₄(Sb₁₇Bi₉)S₄₈.

ozarkite
Thomsonite, a mineral series of the zeolite group.
The mineral mozarkite of the Missouri, Ozark region.

ozarkites
plural of ozarkite

paramorph
A kind of pseudomorph in which there has been a change of physical characteristics without alteration of chemical composition, as in the change of aragonite to calcite.

paramorphs
plural of paramorph

pargasite
A complex inosilicate mineral of the amphibole group.

pargasites
plural of pargasite

paulingite
A rare zeolite mineral found in vesicles in alluvial basaltic rocks.

paulscherrerite
A monoclinic schoepite mineral with chemical formula UO₂(OH)₂.

pedrizite
Any of a group of rare lithium amphibole minerals.

penninite
A double silicate of aluminium and magnesium.

penninites
plural of penninite

pentagonite
A silicate of calcium and vanadium found in basalts and tuffs

perthite
A laminated mixture of two feldspars: plagioclase and either orthoclase or microcline.

perthites
plural of perthite

petalite
A rare pegmatitic mineral, a lithium aluminosilicate, with the chemical formula LiAlSi₄O₁₀; used in the manufacture of crystallized glass ceramics.

petalites
plural of petalite

petrosilex
felsite
A fine-grained, silica-rich rock composed of quartz and sometimes other minerals, similar to the chemical structure of hornstone but having a different texture.

petrosilexes
plural of petrosilex

pezzottaite
A cesium analog of beryl, a silicate of cesium, beryllium, lithium and aluminium that crystallizes in the trigonal system.

pezzottaites
plural of pezzottaite

phaseomannite
inositol

phengite
Any of a series of dioctahedral micas of composition K(AlMg)₂(OH)₂(SiAl)₄O₁₀, similar to muscovite but with addition of magnesium.

phengites
plural of phengite

philippinite
A tektite found in the Philippines.

phillipsite
A mineral of the zeolite group, a hydrated potassium, calcium and aluminium silicate with monoclinic crystals.

philolithite
A tetragonal-ditetragonal dipyramidal mineral with the chemical formula Pb₁₂O₆Mn₇(SO₄)(CO₃)₄Cl₄(OH)₁₂.

phlogopite
A mica mineral with the chemical formula KMg₃AlSi₃O₁₀(F,OH)₂, a basic potassium magnesium aluminosilicate, used as an insulator

phlogopites
plural of phlogopite

phonolite
A light-coloured rock of volcanic origin composed mostly of alkali feldspars.

phonolites
plural of phonolite

phyllosilicate
Any silicate mineral having a crystal structure of parallel sheets of silicate tetrahedra.

phyllosilicates
plural of phyllosilicate

piedmontite
piemontite (a manganic variety of epidote)

piedmontites
plural of piedmontite

piemontite
A monoclinic sorosilicate mineral of the epidote group, reddish in colour.

piemontites
plural of piemontite

pigeonite
Any monoclinic pyroxene that is a mixed calcium, magnesium and ferrous silicate.

pigeonites
plural of pigeonite

pinite
Any fossil wood which exhibits traces of having belonged to the pine family.
A sweet white crystalline substance extracted from the gum of a species of pine (Pinus lambertiana, sugar pine), isomeric with quercite.

pinites
plural of pinite

pistacite
A green variety of epidote that is rich in iron

pistacites
plural of pistacite

pistazite
Alternative form of pistacite.

pistazites
plural of pistazite

plag
plagioclase feldspar

plagioclase
Any of a group of aluminum silicate feldspathic minerals ranging in their ratio of calcium to sodium.

plagioclases
plural of plagioclase

poechite
A silicate mineral with the formula H₁₆Fe₈Mn₂Si₃O₂₀.

polarite
An opaque, yellow-white mineral with a metallic lustre, having the chemical formula (Pd,(Bi,Pb)).

pollucite
A colorless transparent mineral of the zeolite family consisting of hydrous cesium aluminum silicate and occurring massive or crystallizing in cubes.

pollucites
plural of pollucite

polyhydrite
An amorphous aluminosilicate of iron (with some manganese)

poppiite
A greenish-brown monoclinic mineral that is a basic silicate of calcium, vanadium, iron, magnesium and aluminium

porphyroid
A crystalline and schistose rock containing porphyritic crystals of feldspar.

porphyroids
plural of porphyroid

potassicarfvedsonite
Alternative form of potassic-arfvedsonite.

potassicrichterite
Alternative form of potassic-richterite.

prehnite
A mineral, a basic calcium, aluminium and iron aluminosilicate, which occurs in stalactitic aggregates or curved crystals, Ca₂Al₂Si₃O₁₀(OH)₂.

prehnites
plural of prehnite

procerite
The segment next to the flagellum of the antennae of crustaceans.

pseudolaumontite
A hydrous silicate mineral containing aluminium, iron, magnesium and potassium.

pseudowollastonite
A very rare cyclosilicate mineral.

pulaskite
A massive course-grained rock composed chiefly of feldspar with some other minerals such as hornblende and biotite.

pulaskites
plural of pulaskite

pycnochlorite
An iron-rich variety of clinochlore.

pyribole
Any mineral of either the pyroxene or amphibole groups.

pyriboles
plural of pyribole

pyrophyllite
A soft, pale aluminosilicate mineral, somewhat resembling talc.

pyrophyllites
plural of pyrophyllite

pyrosmalite
A mineral, usually of a pale brown or grey-greenish colour, consisting chiefly of the hydrous silicate of iron and manganese.

pyrosmalites
plural of pyrosmalite

pyroxene
Any of a group of crystalline minerals containing silicates of iron, magnesium and calcium.

pyroxenes
plural of pyroxene

pyroxenoid
any of a large group of minerals physically resembling pyroxene

pyroxenoids
plural of pyroxenoid

pyroxferroite
A yellowish silicate of the pyroxene group with a triclinic crystal structure.

pyroxferroites
plural of pyroxferroite

pyrrholite
An aluminosilicate pinite of calcium and potassium

pyrrholites
plural of pyrrholite

qandilite
An opaque black metallic mineral with the chemical formula (Mg,Fe)₂(Ti,Fe,Al)O₄.

qilianshanite
A soft colourless monoclinic mineral with the chemical formula NaHCO₃·H₃BO₃·2H₂O.

qitianlingite
A black orthorhombic mineral with the chemical formula (Fe,Mn)₂(Nb,Ta)₂WO₁₀.

quadruphite
A triclinic sorosilicate mineral.

rensselaerite
A soft, compact variety of talc, being an altered pyroxene, sometimes worked in a lathe into inkstands and other articles, found in New York and Canada.