Sedimentary Or Metamorphic (Low Grade)

Quartzite with Chlorite

Metamorphic Quartzite (SiO2) with phyllosilicates

Blue-gray metamorphic rock fragment

Likely slate or phyllite; exact identification is uncertain from the photograph

Anthracite Coal

Anthracite (Hard Coal)

Likely black shale or slate fragment

Slate; predominantly fine-grained mica/clay minerals and quartz

Tumbled black-and-gold tiger’s-eye

Quartz pseudomorph after crocidolite; SiO₂ with iron oxides

Greenstone or Chlorite Schist

Greenschist / Chlorite schist

Chert / Lake Superior Agate

Cryptocrystalline Silicon Dioxide (SiO2)

Black Opal

Hydrated Silica (SiO2·nH2O)

Emerald In Matrix

Beryl (Be3Al2Si6O18) with trace Chromium/Vanadium

Green Jasper / Metavesuvianite-bearing rock

Silica-rich microcrystalline quartz aggregate / Green Jasper

Mica Schist

Foliated Metamorphic Rock (Schist)

Tiger's Eye

Quartz with riebeckite inclusions (SiO2)

Limonite (Ironstone Concretion)

Hydrous ferric oxides (FeO(OH)·nH2O)

Ironstone Concretion

Ferruginous Concretion (Fe2O3·nH2O)

Fluorite

Calcium Fluoride (CaF2)

Graphitic schist (probable)

Graphite-bearing mica schist; chiefly quartz, mica, and graphite

Green schist (likely chlorite schist)

Chlorite schist; commonly dominated by chlorite, actinolite, epidote, quartz, and feldspar

Greenstone (probable altered basalt)

Chlorite–epidote–actinolite-rich greenschist; composition commonly derived from basalt

Soapstone (talc-rich schist)

Talc schist; chiefly hydrated magnesium silicate, Mg₃Si₄O₁₀(OH)₂

Calcite-rich limestone or marble fragment

Calcite (CaCO₃), likely recrystallized carbonate rock

Likely greenstone (metamorphosed basalt)

Greenschist or chlorite–epidote altered basalt; commonly composed of chlorite, epidote, actinolite, albite, and quartz

Green Greenstone / Celadonite-bearing Metamorphic Rock

Greenschist / Celadonite / Serpentinitic pebble

Greenstone / altered mafic rock

Likely chlorite–actinolite metabasalt (greenschist); exact identification requires testing

Greenstone (Greenschist facies)

Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)

Greenstone

Greenschist (Greened Metabasalt)

Nephrite Jade

Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2), a variety of Actinolite-Tremolite

Greenstone

Metabasalt / Greenschist facies rock

Greenstone

Greenschist / Meta-basalt

Tumbled green serpentine (likely nephrite jade imitation/alternative)

Serpentine-group minerals, chiefly antigorite and lizardite; composition approximately Mg₃Si₂O₅(OH)₄

Greenschist

Greenschist facies rock

Quartz-rich sandstone or quartzite pebble

Likely quartz arenite sandstone; possibly low-grade quartzite, composed mainly of SiO₂

Anthracite Coal with Sulfur staining

Anthracite (Carbon C with impurities)

Greenstone

Metamorphic mafic rock (greenschist facies)

Jadeite (Nephrite-Jadeite blend)

Jadeite (NaAlSi2O6)

Ironstone Concretion

Ferruginous Concretion

Ironstone Concretion

Ironstone (Limonite/Goethite Concretion)

Ironstone Concretion

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Limonite Concretion

Limonite (Hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)

Tumbled tiger’s-eye

Tiger’s-eye (chatoyant quartz), SiO₂, pseudomorphic fibrous quartz after crocidolite

Rounded greenstone cobble

Likely greenschist or altered basalt; composition commonly chlorite, epidote, actinolite, albite, and quartz

Serpentinite

Serpentinite (Hydrated Magnesium Silicate Mg3Si2O5(OH)4)

Greenstone (Epidote/Chlorite-rich Metabasalt)

Greenschist / Epidosite (Ca2(Al,Fe)3(SiO4)3(OH))