Sedimentary Or Metamorphic (Low Grade)

Siltstone

Siltstone

Limonite-stained Quartz / Quartzite

Silicon Dioxide (SiO2) with iron hydroxides (FeO(OH)·nH2O)

Slate

Slate; predominantly fine-grained phyllosilicates (muscovite/illite, chlorite) with quartz and possible iron oxides

Jasper

Microcrystalline Quartz (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Epidote

Epidote (Ca2(Al, Fe)3(SiO4)3(OH))

Greenstone (Prase / Metavolcanic)

Metamorphosed volcanic rock (Greenstone)

Emerald in Matrix (Quartz/Calcite)

Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities

Epidosite (Epidote-rich rock)

Epidotalite (primarily Ca2(Al2Fe3+)(SiO4)(Si2O7)O(OH))

Polished greenstone pebble

Likely serpentinite or chlorite-rich greenschist

Pearl and Garnet Glass

Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass

Green Jasper

Microcrystalline Quartz (SiO2) with inclusions

Jadeite

NaAl(Si2O6)

Anthracite Coal

Anthracite (Carbon based fossil fuel)

Jadeite

NaAl(Si2O6)

Pyrite

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Zoisite with Ruby (Anyolite)

Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)

Mica Schist

Foliated Metamorphic Rock (Schist)

Likely serpentine-rich pebble

Serpentinite, composed mainly of serpentine-group minerals (e.g., antigorite, lizardite, or chrysotile)

Green Quartzite (Aventurine type)

Quartzite (principally Quartz, SiO2) with inclusions of Fuchsite

Black Opal

Hydrated Silica (SiO2·nH2O)

Emerald In Matrix

Beryl (Be3Al2Si6O18) with trace Chromium/Vanadium

Quartzite with Chlorite

Metamorphic Quartzite (SiO2) with phyllosilicates

Aragonite (Flos Ferri)

Calcium Carbonate (CaCO3)

Serpentine

Antigorite-Lizardite-Chrysotile (Mg3Si2O5(OH)4)

Anthracite Coal with Sulfur staining

Anthracite (Carbon C with impurities)

Greenstone (likely chlorite- or actinolite-rich metabasalt)

Metamorphosed mafic volcanic rock; commonly greenschist-facies basalt, composed chiefly of chlorite, actinolite, epidote, and albite

Greenstone (likely altered mafic rock)

Chlorite- and amphibole-bearing metabasalt; exact identification requires testing

Greenstone pebble

Greenstone, typically metamorphosed basalt or andesite; often contains chlorite, epidote, and actinolite

Tumbled greenstone (likely serpentine-rich)

Greenstone; commonly metamorphosed mafic rock composed of actinolite/chlorite with epidote and albite

Likely greenstone (metamorphosed basalt)

Metabasalt; commonly composed of chlorite, actinolite, epidote, and albite

Blue-gray metamorphic rock fragment

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

Anthracite Coal

Anthracite (Hard Coal)

Weathered dark metamorphic rock, likely slate or phyllite

Fine-grained foliated rock, probably slate/phyllite; exact identification requires testing

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)

Weathered greenish mineral specimen, possibly serpentine or epidote

Tentatively serpentine-group mineral (Mg3Si2O5(OH)4) or epidote (Ca2(Al,Fe)3Si3O12(OH)); identification is uncertain from the image alone

Jade (likely Nephrite Jade based on appearance)

Nephrite (a variety of actinolite, Ca2(Mg,Fe)5Si8O22(OH)2)