Metamorphic (Low Grade)

Greenstone / altered basalt (probable)

Chlorite–actinolite–epidote rock; commonly derived from basalt or gabbro

Polished dark stone fragment, possibly slate or schist

Fine-grained foliated metamorphic rock; exact mineral composition is indeterminate from the image

Unakite

Epidote–pink feldspar–quartz rock

Greenstone, likely altered basalt

Metabasalt (chlorite–actinolite–epidote assemblage), likely greenschist-facies greenstone

Green serpentine or nephrite-like stone

Serpentine-group minerals, chiefly antigorite/lizardite; possibly minor chlorite or actinolite

Bornite

Copper Iron Sulfide (Cu5FeS4)

Pink Sapphire

Corundum (Al2O3 with Chromium/Titanium/Iron traces)

Alexandrite in Matrix

Chrysoberyl (BeAl2O4 with Chromium impurities)

Iron-rich quartzite or ironstone

Ferruginous quartzite, likely quartz (SiO₂) with hematite/goethite (Fe₂O₃/FeO(OH))

Tumbled greenstone (likely serpentine or nephrite)

Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly nephrite, a fibrous amphibole aggregate

Blue quartz-bearing rock, possibly chrysocolla-bearing quartzite

Quartz (SiO₂), with probable blue chrysocolla or copper-bearing clay minerals; exact identification requires testing

Rounded calcite-rich limestone or marble pebble

Calcite (CaCO₃), likely recrystallized limestone (marble)

Veined Grey Metamorphic Pebble

Quartzo-feldspathic vein in Metabasalt / Serpentinite / Slate

Anthracite Coal

Anthracite

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Epidote

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

Ironstone Concretion

Siderite or Hematite Concretion

Sapphire Rough (Corundum)

Corundum (Aluminum Oxide, Al2O3)

Anthracite Coal

Anthracite (high-rank coal)

Schist

Mica Schist (primarily Muscovite and Quartz)

Quartz-rich metamorphic pebble, possibly jade-like greenstone

Likely quartzite or altered basalt/greenstone; visible minerals may include quartz, feldspar, chlorite/epidote, and iron oxides

Likely slate or shale fragment

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

Tumbled emerald chips

Emerald, green beryl (Be₃Al₂Si₆O₁₈), colored mainly by chromium and/or vanadium

Mica Schist (with Golden/Biotite inclusions)

K(Mg,Fe)3AlSi3O10(F,OH)2 (Biotite), KAl2(AlSi3O10)(F,OH)2 (Muscovite)

Gold Quartz (Auriferous Quartz)

Silicon Dioxide (SiO2) with trace Gold (Au) and Iron Oxides

Ruby (Rough/Raw)

Corundum (Al2O3:Cr)

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Anthracite Coal

Anthracite

Milky quartz (possibly rose quartz)

Quartz, silicon dioxide (SiO₂)

Likely serpentinite

Serpentinite, composed mainly of serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and minor chromite

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Likely blue-gray stone, possibly slate or basalt

Indeterminate; candidates include slate (fine-grained metamorphic rock) or basalt (mafic igneous rock)

Serpentine-rich altered ultramafic rock

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite and carbonate

Serpentine (likely serpentine-rich pebble)

Serpentine-group minerals, chiefly antigorite and/or lizardite; commonly associated with magnetite and chlorite

Ruby (Faceted)

Corundum (Al2O3 with Cr trace elements)

Anthracite Coal

Anthracite (Carbon-rich mineraloid)

White quartz-rich pebble, possibly milky quartz

Quartz (silicon dioxide, SiO₂), likely massive milky quartz

Serpentine (likely polished serpentine pebble)

Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; approximate formula Mg₃Si₂O₅(OH)₄

Celadonite in Basalt (Green Earth)

Celadonite (K(Mg,Fe2+)(Fe3+,Al)Si4O10(OH)2)

Marble

Crystalline Limestone (mostly CaCO3 / Calcium Carbonate)

Raw Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Milky quartz pebble

Quartz, silicon dioxide (SiO₂), cryptocrystalline to microcrystalline variety