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Every stone, A to Z

Every one of them with its species, chemistry, hardness, refractive index, density, origins and treatment reality written out — including the cases where the honest answer is that a treatment cannot be detected at all.

671Stones

91Countries of origin

10Colour families

A

Abalone PearlNacreous pearl, usually a horn-shaped blister, from Haliotis species Abalone ShellNacreous shell of Haliotis species - the most strongly iridescent natural nacre AchroiteElbaite (tourmaline supergroup) ActinoliteActinolite (amphibole group) AdamiteAdamite AdulariaFeldspar group (alkali) AegirineAegirine (pyroxene group) AfghaniteCancrinite group (feldspathoid) AgateChalcedony Agatised Dinosaur BoneChalcedony/quartz replacing fossil bone Agatized CoralOligocene-Miocene scleractinian coral colonies in which the aragonite skeleton has been replaced by chalcedony - a fossil, and silica, not carbonate Agatized Dinosaur BoneFossil dinosaur bone in which the marrow cavities have been filled with agate, chalcedony or jasper while the bone cell walls are preserved Aka CoralCalcareous skeleton of the deep-water octocoral Corallium japonicum Akoya Cultured PearlBead-nucleated cultured pearl from Pinctada fucata martensii AlabasterGypsum (or calcite alabaster) AlbiteAlbite (plagioclase feldspar) AlexandriteChrysoberyl AllaniteEpidote group AlmandineAlmandine garnet AmatriceVariscite and turquoise in a silicified matrix AmazoniteMicrocline feldspar AmberFossil tree resin AmblygoniteAmblygonite–montebrasite series AmethystQuartz AmetrineQuartz AmmoliteFossil ammonite nacre AnalcimeAnalcime (zeolite group) AnataseRutile group polymorph AndalusiteAndalusite AndesineAndesine (plagioclase feldspar) AndraditeGarnet group Angel Skin CoralThe pale, evenly-coloured pink to near-white grade of Pleurocorallium elatius and related species AnglesiteBarite group AnhydriteAnhydrite AnorthiteFeldspar group (plagioclase) AnorthoclaseFeldspar group (alkali) AnthophylliteAmphibole group (orthoamphibole) AntigoriteSerpentine subgroup AnyoliteA metamorphic rock: green zoisite with pink-red corundum crystals and black pargasite amphibole Apache TearsVolcanic glass (marekanite) ApatiteApatite ApophylliteFluorapophyllite-(K) Aqua AuraCoated quartz AquamarineBeryl AquapraseChalcedony AragoniteAragonite AstrophylliteAstrophyllite AtacamiteAtacamite AugeliteAugelite AugitePyroxene group AurichalciteAurichalcite AustraliteThe Australian member of the Australasian tektite strewn field, distinguished by aerodynamic ablation flanges on button forms AventurineQuartzite Aventurine QuartziteQuartzite - a metamorphosed sandstone - containing reflective platy mineral inclusions that give aventurescence AxiniteAxinite group AzuriteAzurite AzurmalachiteAzurite–malachite intergrowth

B

BaddeleyiteZirconium oxide Baltic AmberFossil conifer resin, Eocene (34-48 Ma), from Pinus succinifera-type trees Bamboo CoralCalcitic internodes of deep-sea isidid gorgonians, alternating with dark horny nodes - hence the bamboo look BariteBarium sulphate BasaltVolcanic rock BastiteSerpentine pseudomorph BastnäsiteRare-earth fluorocarbonate BenitoiteBenitoite BentoniteA clay rock formed by the in-situ alteration of volcanic ash, dominated by the swelling smectite mineral montmorillonite BertranditeBeryllium silicate BerylBeryl BerylloniteBeryllonite Biggs JasperJasper (silicified volcanic ash) BinghamiteChalcedony with goethite and hematite fibres BixbyiteBixbyite Black CoralHorny proteinaceous skeleton of antipatharian corals - not carbonate at all Black opalHydrated silica Bloodshot IoliteCordierite BloodstoneChalcedony Blue AmberFossil Hymenaea resin that fluoresces strongly blue under daylight UV; the body colour itself is honey-brown Blue CoralAragonitic skeleton of Heliopora coerulea, the only octocoral with a massive aragonite skeleton Blue JohnFluorite (banded variety) Blue Lace AgateChalcedony (banded) Blue TopazTopaz Blue ZirconZircon BoleiteBoleite BoneSkeletal tissue, chiefly bovine, camel and buffalo, used as an ivory substitute BoraciteBoracite BoraxBorax BorniteBornite Botswana AgateChalcedony (agate) Boulder OpalOpal in ironstone matrix BournoniteBournonite BoweniteAntigorite (serpentine group) BrazilianiteBrazilianite BrochantiteBrochantite BronziteEnstatite–ferrosilite series (pyroxene group) BrookiteRutile group polymorph BruciteBrucite Bruneau JasperJasper (silicified rhyolite) Bumblebee StoneBanded volcanic sediment of calcite, gypsum, sulphur, realgar and orpiment from a fumarolic setting - not a jasper and containing no chalcedony BurmiteFossil conifer resin, mid-Cretaceous, approx. 99 Ma - the oldest amber in regular commercial use BustamiteBustamite (pyroxenoid) BytowniteBytownite (plagioclase feldspar)

C

CacholongOpal (porous common opal) CalciteCalcite CaledoniteLead-copper sulphate-carbonate CaliforniteVesuvianite (massive) Cameo ShellThick helmet-shell wall with contrasting colour layers, carved in relief CampbelliteBrecciated copper secondary minerals in silica Canary TourmalineTourmaline supergroup (elbaite) CancriniteFeldspathoid CarletonitePotassium-sodium-calcium silicate CarnelianChalcedony CassiteriteCassiterite Cat's Eye ApatiteApatite group Cat's Eye AquamarineBeryl Cat’s eye chrysoberylChrysoberyl Cat's Eye OpalCommon or precious opal Cat's Eye ScapoliteScapolite group Cat's Eye SillimaniteSillimanite Cat's Eye TourmalineElbaite (tourmaline supergroup) CatapleiiteZirconium silicate CavansiteCavansite CelestineCelestine CerussiteAragonite group CeyloniteSpinel group (variety) ChabaziteZeolite group ChalcanthiteChalcanthite ChalcedonyChalcedony ChalcopyriteChalcopyrite ChambersiteBoracite group CharnockiteOrthopyroxene-bearing granitoid, formed at granulite-facies conditions - a distinct petrological rock type, not a trade name CharoiteCharoite ChiastoliteAndalusite ChildreniteChildrenite-eosphorite series ChlorastrolitePumpellyite ChondroditeChondrodite (humite group) Chrome DiopsideDiopside (pyroxene group) Chrome PyropeGarnet group (pyrope) Chrome tourmalineDravite tourmaline Chrome TremoliteAmphibole group ChromiteSpinel group Chromite (Foundry and Refractory)An iron-chromium spinel oxide; the foundry and refractory grades exploit its high melting point, thermal conductivity and chemical resistance to basic slags Chrysanthemum StoneOrnamental sedimentary rock ChrysoberylChrysoberyl ChrysocollaCopper silicate ChrysopraseChalcedony ChrysotileSerpentine subgroup CinnabarCinnabar CitrineQuartz ClinochloreChlorite group ClinohedriteZinc-calcium silicate ClinohumiteClinohumite (humite group) ClinozoisiteClinozoisite Cobalt spinelSpinel CobaltiteCobaltite Cobaltoan CalciteCalcite (Co-bearing variety) ColemaniteColemanite Colour-change garnetPyrope–spessartine garnet Colour-change SapphireCorundum Colourless TopazTopaz Common OpalOpal Conch PearlNon-nacreous calcareous concretion from the queen conch Aliger gigas (formerly Strombus gigas) CopalSub-fossil tree resin, typically a few hundred to a few hundred thousand years old - not amber CopperCopper (native element) CoralCalcium carbonate skeleton of marine polyps Cordierite (Technical Ceramic)A magnesium aluminosilicate with a near-zero coefficient of thermal expansion, which makes it the standard material for thermal-shock-resistant ceramics - though the technical product is almost always synthesised, not mined CorundumCorundum CoticuleA metamorphic rock in which 5-20 micrometre spessartine garnet crystals are dispersed through a mica-rich phyllite matrix - a natural garnet abrasive in a self-releasing binder CovelliteCovellite Crazy Lace AgateChalcedony (agate) CreediteCalcium aluminium fluoride-sulphate Crinoidal LimestoneLimestone composed largely of crinoid ossicles, which polish to a distinctive spangled pattern CrocoiteCrocoite CryoliteCryolite Cubic ZirconiaSynthetic yttria- or calcia-stabilised zirconium oxide CupriteCuprite CyprineVesuvianite (trade usage) — note the IMA species cyprine is a different, red mineral

D

DallasiteSilicified volcanic breccia Dalmatian StoneQuartz-feldspar porphyry - a fine-grained igneous rock with dark phenocrysts; not a jasper and not chalcedony DanburiteDanburite Darwin GlassAn impactite natural glass from the Darwin Crater impact, approximately 816,000 years old DatoliteDatolite DemantoidAndradite garnet Dendritic AgateChalcedony DescloiziteDescloizite–mottramite series DiallagePyroxene (textural variety) DiamondDiamond DiasporeDiaspore DiatomiteA sedimentary rock composed of the opaline silica frustules of fossil diatoms - a biogenic silica with extraordinary porosity DiopsideDiopside (pyroxene group) DioptaseDioptase DolomiteDolomite Dolomite (Industrial)A calcium-magnesium carbonate rock, used as a flux, refractory, filler and as the feedstock for magnesium metal Dominican AmberFossil resin of Hymenaea protera, Miocene, approx. 16-20 Ma DraviteDravite (tourmaline supergroup) DumortieriteDumortierite Dumortierite QuartzQuartz with dumortierite inclusions

E

EclogiteA high-pressure metamorphic rock of red pyrope-almandine garnet in green omphacite pyroxene, formed in subduction zones Eilat StoneIntergrowth of chrysocolla, malachite, turquoise and other copper secondaries EkaniteThorium calcium silicate ElaeoliteFeldspathoid (nepheline variety) Elephant IvoryDentine from the tusks of Loxodonta africana and Elephas maximus EmeraldBeryl EmeryA naturally occurring abrasive rock - an intergrowth of corundum with magnetite, hercynite spinel and hematite Enhydro AgateChalcedony (agate) EnstatiteEnstatite (pyroxene group) EosphoriteEosphorite–childrenite series EpidoteEpidote ErythriteVivianite group EsperiteLead-zinc silicate Ethiopian OpalOpal (hydrophane) EttringiteEttringite EuclaseEuclase EudialyteEudialyte group Eudialyte-Bearing Agpaitic RockLayered agpaitic nepheline syenite in which pink eudialyte forms the ornamental component, with black arfvedsonite and white feldspar

F

Fairburn AgateChalcedony (agate) FaustiteTurquoise group FayaliteOlivine group Feldspar (Industrial)Alkali and plagioclase feldspars used as a flux to lower melting temperature in glass and ceramics - the single largest industrial use of any silicate after quartz FerberiteWolframite group Fire AgateChalcedony Fire ObsidianObsidian containing extremely thin, regular layers of magnetite nanocrystals that act as an optical thin-film stack Fire opalHydrated silica FlintChalcedony (microcrystalline quartz) Fluor-buergeriteTourmaline supergroup FluoriteFluorite FluorsparCalcium fluoride, the sole significant commercial source of fluorine for the entire chemical industry FoititeTourmaline supergroup ForditeMan-made: baked automotive lacquer overspray ForsteriteOlivine group Fossil AmmoniteFossil shell of Mesozoic cephalopods, preserved as calcite, aragonite, pyrite or as an internal mould Fossil Palm WoodSilicified fossil palm stem Fossil Shark ToothFossil vertebrate tooth, mineralised FrankliniteSpinel group Freshwater Cultured PearlMostly tissue-nucleated (non-beaded) cultured pearl from the triangle mussel Hyriopsis cumingii and hybrids FriedeliteManganese phyllosilicate FuchsiteMuscovite (mica group) Fuller's EarthA general term for absorbent clays - chiefly palygorskite/attapulgite and calcium montmorillonite - used for their adsorptive and decolourising capacity rather than a defined mineral

G

Gadolinium Gallium GarnetSynthetic garnet-structure oxide GahniteSpinel group GahnospinelSpinel group (Zn-bearing spinel) GalenaGalena Garnet (Industrial Abrasive)Crushed and graded almandine or andradite garnet, used as a cutting and blasting abrasive because it fractures to fresh sharp edges and is low in free silica GarnieriteMixture of nickel-bearing serpentine and talc minerals GaspéiteCalcite group GedriteAmphibole group (orthoamphibole) Gem SilicaChalcedony with chrysocolla inclusions Giant Clam ShellDense white shell of Tridacna gigas, T. squamosa and related giant clams GneissHigh-grade metamorphic rock with a banded segregation of light feldspar-quartz and dark mica-amphibole layers GoethiteGoethite GoldGold (native element) Golden CoralProteinaceous skeleton of Kulamanamana haumeaae, a zoanthid that overgrows black coral, plus some bleached Antipatharia sold under the same name Golden Sheen ObsidianObsidian with a single golden sheen produced by aligned gas bubbles or nanoscale inclusions in the flow banding GoldstoneMan-made glass with copper crystals GosheniteBeryl GrandidieriteGrandidierite GraniteCoarse-grained felsic intrusive igneous rock of quartz, alkali feldspar and plagioclase; in the stone trade the word also covers gabbro, anorthosite, gneiss and charnockite GraphiteGraphite (native element) Green ZirconZircon Green ZoisiteZoisite GrossularGrossular (garnet group) GypsumGypsum Gypsum (Industrial)Hydrated calcium sulphate, calcined to plaster of Paris and stucco, and the basis of the entire wallboard industry

H

HackmaniteSodalite HalloysiteA kaolin-group clay mineral that grows as hollow nanotubes rather than plates, which is the basis of its speciality value HambergiteHambergite HardystoniteMelilite group Harlequin OpalPrecious opal HaüyneHaüyne (sodalite group) Hawk's EyeQuartz (silicified crocidolite) HeliodorBeryl HematiteIron oxide HemimorphiteHemimorphite HercyniteSpinel group HessoniteGrossular garnet HexagoniteTremolite (amphibole group) HiboniteHibonite HiddeniteSpodumene High-Purity QuartzQuartz refined to extreme chemical purity, used for the crucibles in which silicon is melted for semiconductors and solar wafers - a genuine strategic material Himalayan saltHalite Hippopotamus IvoryCanine and incisor dentine of Hippopotamus amphibius - harder and whiter than elephant ivory, and slower to yellow HodgkinsoniteZinc-manganese silicate HolmquistiteAmphibole group (lithium amphibole) HornKeratinous sheath of bovid horn - water buffalo, cattle, and historically rhinoceros (which is a different legal matter entirely) HowliteBorate HübneriteWolframite series HumiteHumite group HureauliteManganese phosphate HurlbutiteBeryllium phosphate HyacinthZircon (variety) Hyalite OpalOpal HydrogrossularGrossular–hibschite series (garnet group) HydroxylherderiteHerderite–hydroxylherderite series HyperstheneEnstatite–ferrosilite series (pyroxene group)

I

IlmeniteIlmenite group Imperial JasperJasper (orbicular, silicified volcanic) Imperial topazTopaz InderiteMagnesium borate IndicoliteElbaite tourmaline IndochiniteA tektite of the Australasian strewn field, formed approximately 790,000 years ago by an as-yet-unlocated impact Industrial Silica SandWell-sorted, well-rounded, high-purity quartz sand, graded for glassmaking, foundry moulding and hydraulic-fracturing proppant IoliteCordierite Iris AgateChalcedony (agate) IrnimiteJasper with Ba-Mn silicate veins Iron MeteoriteThe metallic core material of a differentiated asteroid - an intergrowth of the nickel-iron alloys kamacite and taenite ItacolumiteA porous quartzite or micaceous sandstone whose interlocking grains have enough space to hinge, so thin slabs genuinely bend

J

JacobsiteSpinel group JadeiteJadeite pyroxene Japanese Natural WhetstoneFine-grained sedimentary rocks - chiefly radiolarian mudstone and volcanic tuff from the Tamba belt - whose micron-scale silica particles break down into a self-generating polishing slurry JasperChalcedony (opaque) JeremejeviteJeremejevite JetLignite — fossilised wood JohachidoliteCalcium aluminium borate

K

Kambaba StoneSilicified microgranular igneous or volcaniclastic rock with orbicular green-and-black rings; often sold as a fossil stromatolite, which recent petrographic work does not support KämmereriteClinochlore (chlorite group) KaolinA clay rock dominated by kaolinite, formed by weathering or hydrothermal alteration of feldspar in granite and arkose KerniteKernite Keshi PearlNon-beaded pearl formed accidentally in a cultured oyster after bead rejection - solid nacre, but a by-product of culturing KornerupineKornerupine KunziteSpodumene KyaniteKyanite

L

LabradoritePlagioclase feldspar Laguna AgateChalcedony (agate) Lake Superior AgateChalcedony (agate) Landscape MarbleA fine-grained limestone or calcareous marl whose fracture network has been infiltrated by iron oxides, producing images of ruined cities and coastlines Lapis lazuliRock — lazurite with calcite and pyrite LarimarPectolite LarvikiteMonzonite rock (ternary feldspar) Lava rockVesicular volcanic rock Lavender JadeiteJadeite (pyroxene group) LavrovitePyroxene group (diopside variety) LazuliteLazulite–scorzalite series LazuriteLazurite (sodalite group) LeadhilliteLeadhillite LegranditeLegrandite Leopard Skin JasperOrbicular rhyolite with spherulitic rings in a fine volcanic groundmass - again a rhyolite rather than a true jasper LepidoliteLepidolite series (mica group) LeuciteFeldspathoid Leuco GarnetGrossular (garnet group) Libyan Desert GlassImpact glass LiddicoatiteLiddicoatite (tourmaline supergroup) LimestoneSedimentary carbonate rock, chiefly of biogenic or chemically precipitated calcite LinariteLinarite LizarditeSerpentine subgroup LlaniteRhyolite porphyry LodoliteQuartz with chlorite/clay inclusions LondoniteRhodizite-londonite series LudlamiteLudlamite LumachellaA fossiliferous limestone packed with iridescent shell fragments - typically ammonite or gastropod nacre preserved in a dark carbonate matrix Lunar MeteoriteRock ejected from the Moon by an impact and later fallen to Earth - chiefly feldspathic highland breccia, mare basalt or a mingled breccia

M

Mabe PearlAssembled product: a hemispherical nacre dome cultured against the shell, cut out, backed and capped MacusanitePeraluminous rhyolitic volcanic glass Magnesio-axiniteAxinite group MagnesiteMagnesite Magnesite and Dead-Burned MagnesiaMagnesium carbonate rock calcined at very high temperature to dense periclase, the workhorse basic refractory for steelmaking MagnetiteSpinel group Mahogany ObsidianObsidian with red-brown bands and patches produced by oxidised iron inclusions MalachiteCopper carbonate Malaia garnetPyrope–spessartine garnet Mali GarnetGrossular–andradite (garnet group) Mammoth IvoryDentine from the tusks of the extinct woolly mammoth Mammuthus primigenius, typically 10,000-40,000 years old ManganaxiniteAxinite group ManganiteManganite ManganotantaliteColumbite-tantalite group MarbleMetamorphosed limestone MarcasiteMarcasite MarialiteScapolite group Martian MeteoriteIgneous rock ejected from Mars by impact - proven Martian by trapped atmospheric gas matching Viking measurements Matrix OpalPrecious opal within a porous host rock Maw-sit-sitKosmochlor-bearing rock Maxixe BerylBeryl Mediterranean Red CoralCalcareous axial skeleton of the gorgonian octocoral Corallium rubrum MeerschaumSepiolite MeioniteScapolite group MelaniteAndradite (garnet group) MelliteOrganic mineral (aluminium mellitate) Melo PearlNon-nacreous calcareous concretion from the large marine gastropod Melo melo MerliniteChalcedony or common opal with manganese oxide dendrites MeteoriteIron–nickel, stony, or stony-iron Meteoritic IronKamacite–taenite alloy (native element) Mexican AmberFossil resin of Hymenaea, Miocene, approx. 22-26 Ma Mexican OnyxCalcite (banded travertine) MicaMica group — muscovite, phlogopite Mica (Industrial)Sheet silicate minerals with perfect basal cleavage, split into thin flexible transparent laminae; supplied as sheet, block, splittings, or ground flake MicroclineFeldspar group MicrolitePyrochlore supergroup MilariteMilarite (osumilite group) Milky QuartzQuartz MilleriteMillerite MimetiteApatite supergroup Mint GarnetGrossular (garnet group) MohawkiteDomeykite and algodonite with native copper in quartz MoldaviteTektite — impact glass MolybdeniteMolybdenite Momo CoralCalcareous skeleton of the octocoral Pleurocorallium (Corallium) elatius MonaziteRare-earth phosphate MontebrasiteAmblygonite-montebrasite series MookaiteChalcedony / radiolarite MoonstoneOrthoclase / albite feldspar MorganiteBeryl MorionQuartz (variety) Moss AgateChalcedony Mother-of-PearlThe nacreous inner shell layer of pearl oysters and freshwater mussels MtoroliteChalcedony MuscoviteMuscovite (mica group) MusgraviteMagnesiotaaffeite-6N’3S MyrickiteChalcedony or common opal with cinnabar Mystic TopazTopaz

N

NarsarsukiteSodium titanium silicate Narwhal IvoryMarine mammal tooth (Monodon monoceros) NatroliteNatrolite (zeolite group) Natural GraphiteThe soft, layered, electrically conductive polymorph of carbon; supplied as flake, vein (lump) or microcrystalline (misleadingly called amorphous) Natural PearlNacre formed without human intervention around an irritant inside a wild pearl oyster, chiefly Pinctada radiata and P. persica Natural PozzolanVolcanic ash, tuff and pumicite that reacts with lime in the presence of water to form cementitious compounds - the original hydraulic binder, and now a major route to lower-carbon concrete Natural Zeolite (Clinoptilolite)A hydrated alkali aluminosilicate with an open microporous framework, mined from altered volcanic tuff and used as a molecular sieve and ion exchanger Nebula StoneAn unusual alkaline igneous rock of quartz, aegirine, riebeckite and anorthoclase with green orbs in a black ground; a registered trade name from a single deposit NephelineFeldspathoid NephriteTremolite–actinolite amphibole NeptuniteNeptunite NifontoviteCalcium borate NorbergiteHumite group NoseanSodalite group (feldspathoid) NovaculiteMicrocrystalline quartz NuummiteAnthophyllite–gedrite rock (amphibole group)

O

ObsidianVolcanic glass Ocean JasperChalcedony (orbicular) OdontoliteFossil mammal bone and ivory (mastodon, dinotherium) coloured blue by vivianite, then heated - not turquoise OligoclaseFeldspar group (plagioclase) Olivine (Foundry and Industrial)Crushed dunite - a near-monomineralic olivine rock - used as foundry moulding sand, slag conditioner and refractory, and increasingly for carbon mineralisation Omphacite JadeOmphacite (pyroxene group) OnyxChalcedony (banded) / calcite (architectural) OpalHydrated silica OperculumCalcareous trapdoor (operculum) of the turban snail Turbo petholatus and related species OphicalciteMetamorphic rock Ordinary ChondriteThe commonest meteorite type: undifferentiated primitive stone containing chondrules - millimetre-scale melt droplets from the early solar nebula, about 4.56 billion years old Oregon SunstoneLabradorite (plagioclase feldspar) OrpimentOrpiment OrthocerasDevonian nautiloid cephalopod shells preserved in a black bituminous limestone, cut and polished as slabs OrthoclaseOrthoclase (feldspar group)

P

PadparadschaCorundum PainitePainite PallasiteA stony-iron meteorite: gem olivine crystals suspended in a nickel-iron matrix, thought to form at the core-mantle boundary of a differentiated asteroid PapagoiteCopper-calcium silicate Paraíba tourmalineElbaite tourmaline PargasitePargasite (amphibole group) ParisiteRare-earth fluorocarbonate PasteMan-made glass Peanut WoodSilicified fossil driftwood bored by bivalves PearlNacre — aragonite and conchiolin PectoliteWollastonite group PeridotOlivine (forsterite–fayalite) PerliteA hydrated volcanic glass containing 2-5% combined water, which expands into a lightweight froth when heated rapidly to 850-900 C PerovskitePerovskite PerthiteFeldspar intergrowth PetalitePetalite Petoskey StoneFossil rugose coral in limestone Petrified WoodChalcedony / opal replacing wood PezzottaitePezzottaite (beryl group) PhenakitePhenakite PhosgenitePhosgenite PhosphophyllitePhosphophyllite PhosphosideriteIron phosphate Picture JasperChalcedony / silicified sediment PietersiteQuartz (brecciated silicified amphibole) Pink OpalCommon opal Pink SapphireCorundum PipestoneA fine-grained red argillite - a metamorphosed clay-rich sediment - soft enough to carve with a knife PlasmaChalcedony PlatinumPlatinum (native element) Plume AgateChalcedony (agate) PollucitePollucite (zeolite group) Poppy JasperBrecciated and orbicular silicified volcanic rock with red and yellow orbs in a darker ground PoudretteitePoudretteite (osumilite group) PovondraiteTourmaline supergroup PowelliteScheelite group PraseQuartz with actinolite inclusions Prase OpalCommon opal PrasioliteQuartz Precious OpalOpal PrehnitePrehnite Preseli BluestoneSpotted dolerite - a medium-grained mafic intrusive rock with white plagioclase-rich spots in a blue-grey ground Pressed AmberGenuine amber chips and dust fused under heat (approx. 200-250 C) and pressure into blocks ProustiteProustite PsilomelaneField term for botryoidal manganese oxides, chiefly romanèchite PumiceVesicular volcanic glass PurpuritePurpurite–heterosite series PyrargyritePyrargyrite PyriteIron sulphide PyrolusitePyrolusite PyromorphiteApatite supergroup PyropePyrope garnet PyrophyllitePyrophyllite PyroxmangitePyroxenoid

Q

Quahog PearlNon-nacreous concretion from the hard clam Mercenaria mercenaria QuartzQuartz Quartz Cat's EyeQuartz QuartziteMetamorphic rock (quartz) Queen Conch ShellShell of the large Caribbean gastropod Aliger gigas, used for carving, beads and cameo

R

Rainbow GarnetGarnet group (andradite) Rainbow Lattice SunstoneOrthoclase feldspar with oriented inclusions Rainbow MoonstoneLabradorite (plagioclase feldspar) Rainbow ObsidianVolcanic glass Rainforest JasperSpherulitic rhyolite - a volcanic rock with radial devitrification spherulites - not a jasper RealgarRealgar Red BerylBeryl Refractory-Grade BauxiteBauxite - an aluminium-hydroxide rock - selected for low iron and silica and calcined to a dense, hard, high-alumina refractory aggregate RhodiziteRhodizite–londonite series RhodochrositeManganese carbonate RhodolitePyrope–almandine garnet RhodoniteManganese silicate Rock crystalQuartz RomanèchiteBarium manganese oxide RosasiteRosasite Rose quartzQuartz RossmaniteTourmaline supergroup RubelliteElbaite tourmaline RubyCorundum Ruby in FuchsiteCorundum in chromian muscovite rock RumaniteFossil resin Rutilated QuartzQuartz with rutile inclusions RutileRutile

S

SandstoneClastic sedimentary rock of cemented sand-grade grains, dominantly quartz SanidineSanidine (feldspar group) SapphireCorundum SapphirineSapphirine SardChalcedony SardonyxChalcedony (banded) Scallop PearlNon-nacreous pearl from the scallop Nodipecten subnodosus ScapoliteMarialite–meionite series ScheeliteScheelite SchorlSchorl tourmaline SchorlomiteGarnet group SchulteniteLead arsenate ScoleciteScolecite (zeolite group) ScoroditeScorodite ScorzaliteLazulite-scorzalite series SeleniteGypsum SellaiteMagnesium fluoride SepioliteA fibrous hydrated magnesium silicate clay; the massive nodular form is the classic pipe-carving meerschaum, while the bulk mineral is an industrial absorbent and rheology additive Septarian NoduleCarbonate concretion whose internal shrinkage cracks have been filled with yellow calcite and brown aragonite - a concretion, not a single mineral SeranditeWollastonite group SeraphiniteClinochlore (chlorite group) SerendibiteSerendibite SerpentineSerpentine group SerpentiniteA metamorphic rock of serpentine-group minerals formed by hydration of ultramafic rock ShattuckiteShattuckite ShortiteSodium-calcium carbonate ShungiteCarbonaceous rock SideriteSiderite SillimaniteSillimanite SilverSilver (native element) SimetiteFossil resin SimpsoniteAluminium tantalate SinhaliteSinhalite SlateMetamorphosed shale SmaragditeAmphibole group (variety) SmithsoniteSmithsonite Smoky quartzQuartz Snowflake ObsidianVolcanic glass SoapstoneTalc-rich metamorphic rock SodaliteSodalite SogdianiteMilarite group (sugilite relative) SonoliteHumite group South Sea Cultured PearlBead-nucleated cultured pearl from the silver-lipped and gold-lipped oyster Pinctada maxima SpectroliteLabradorite (plagioclase feldspar) Sperm Whale IvoryMarine mammal tooth (Physeter macrocephalus) SpessartiteSpessartine (garnet group) SphaleriteSphalerite SpheneTitanite SpinelSpinel SpodumenePyroxene group Sponge CoralPorous calcareous skeleton of melithaeid gorgonians and similar reef corals Star DiopsideDiopside (pyroxene group) Star GarnetGarnet group (almandine) Star Rose QuartzQuartz Star RubyCorundum Star sapphireCorundum Star SpinelSpinel StauroliteStaurolite StibiotantaliteAntimony tantalate StibniteStibnite StichtiteHydrotalcite group StilbiteStilbite-Ca (zeolite group) Strawberry QuartzQuartz with lepidocrocite/hematite inclusions StromatoliteLaminated sedimentary structure built by microbial mats trapping and precipitating carbonate - among the oldest evidence of life on Earth StrontianiteAragonite group Strontium TitanateSynthetic perovskite-structure oxide SueviteAn impact breccia of shocked mineral and rock fragments in a partly melted glassy matrix, formed inside an impact crater SugiliteSugilite SulphurSulphur (native element) SunstoneFeldspar Sunstone (Oligoclase)Oligoclase (plagioclase feldspar) SussexiteManganese borate SylviteHalite group Synthetic MoissaniteSynthetic silicon carbide

T

TaaffeiteTaaffeite TaguaHardened endosperm of the seed of the tagua palm Phytelephas macrocarpa and P. aequatorialis Tahitian Cultured PearlBead-nucleated cultured pearl from the black-lipped oyster Pinctada margaritifera Talc (Industrial)The softest mineral on the Mohs scale, a hydrated magnesium sheet silicate, valued industrially for platyness, softness, inertness and hydrophobicity TantaliteColumbite-tantalite group TanzaniteZoisite TawmawiteEpidote TektiteImpact glass ThaumasiteCalcium silicate-carbonate-sulphate ThomsoniteThomsonite-Ca (zeolite group) ThuliteZoisite Thunder EggRhyolite nodule with a chalcedony or agate core Thuringian Water HoneA very fine-grained Ordovician-Silurian slate from the Thuringian Slate Mountains, used as a razor finishing hone Tiffany StoneBeryllium-bearing opalised fluorite breccia Tiger IronBanded iron formation (chalcedony + hematite) Tiger’s eyeQuartz after crocidolite TinzeniteAxinite group Titanium QuartzCoated quartz TopazTopaz TopazoliteAndradite (garnet group) TortoiseshellKeratinous carapace scutes of the hawksbill sea turtle Eretmochelys imbricata Tourmalinated QuartzQuartz with schorl inclusions Tourmaline (Elbaite)Elbaite (tourmaline supergroup) Trapiche EmeraldBeryl Trapiche RubyCorundum TravertineFreshwater limestone TremoliteTremolite (amphibole group) TrilobiteFossil arthropod exoskeleton, Cambrian to Permian, preserved in limestone, shale or as a calcite replacement TriphaneSpodumene (pyroxene group) TripliteManganese phosphate TripoliA friable, extremely fine-grained microcrystalline silica formed by the leaching of carbonate out of siliceous limestone, leaving a porous silica residue TsavoriteGrossular garnet TugtupiteTugtupite (sodalite group) TurquoiseTurquoise Turritella AgateChalcedony with fossil gastropods

U

UlexiteUlexite UmbaliteGarnet group (pyrope-spessartine) UnakiteAltered granite (epidote + orthoclase + quartz) UvaroviteUvarovite (garnet group) UviteUvite (tourmaline supergroup)

V

VanadiniteApatite supergroup VarisciteVariscite Vegetable ivoryTagua palm endosperm VerdeliteElbaite (tourmaline supergroup) VerditeFuchsite-rich metamorphic rock VermiculiteA hydrated magnesium-aluminium sheet silicate, an alteration product of biotite and phlogopite, which exfoliates dramatically on rapid heating as interlayer water flashes to steam Verneuil Synthetic CorundumSynthetic corundum VesuvianiteVesuvianite VilliaumiteVilliaumite ViolaneDiopside (pyroxene group) ViridineAndalusite (variety) VivianiteVivianite

W

Walrus IvoryTusk dentine of Odobenus rosmarus, with a distinctive marbled secondary dentine core WarditeWardite Warthog IvorySuid tooth (Phacochoerus africanus) Watermelon tourmalineElbaite tourmaline WavelliteWavellite White Precious CoralCalcareous skeleton of the white precious coral Pleurocorallium (Corallium) konojoi WhitlockiteCalcium phosphate WillemiteWillemite WilliamsiteAntigorite (serpentine group) WitheriteAragonite group WollastoniteWollastonite (pyroxenoid) WonderstoneBanded rhyolitic tuff coloured by iron oxide staining in concentric and wavy Liesegang bands Wood TinCassiterite (variety) WulfeniteWulfenite

X

XenotimeRare-earth phosphate XonotliteCalcium silicate

Y

Yellow SapphireCorundum Yttrium Aluminium GarnetSynthetic garnet-structure oxide

Z

Zebra StoneNeoproterozoic siltstone with rhythmic red hematite bands, stripes and spots in a white-cream ground - a self-organised chemical banding in a sediment ZektzeriteTuhualite group ZeoliteZeolite group — stilbite, heulandite, apophyllite ZinciteZincite ZirconZircon Zircon (Foundry and Refractory Sand)Zirconium silicate recovered as a co-product of heavy mineral sand mining for titanium minerals; used for its refractoriness, low thermal expansion and opacity ZoisiteZoisite