Sedimentary Rock (Altered)

Mixed river stones; foreground likely sandstone

Quartz-rich sandstone, with associated rounded quartzite/chert and other cobbles

Weathered, biotite-bearing granite or granitic gneiss

Quartz–feldspar–biotite rock; likely granite (compositionally, quartz + K-feldspar/plagioclase + biotite), possibly weakly foliated gneiss

Weathered igneous pebble, likely basaltic andesite

Fine-grained mafic to intermediate volcanic rock; chiefly plagioclase feldspar, pyroxene, and possibly olivine or magnetite

Banded limestone or marble

Calcite-dominated carbonate rock; likely banded marble (CaCO₃)

Green stone fragment (unidentified)

Undetermined; possibly serpentine or greenstone, but the image is insufficient for identification

Banded River Cobble with Mafic Dike

Hydrothermally altered Graywacke or Sandstone with Mafic Intrusion

Tumbled yellow jasper (likely serpentine or calcite-rich stone)

Jasper: microcrystalline quartz (SiO₂); exact yellow veining may indicate serpentine, calcite, or iron oxides

Mixed river-worn rock and mineral collection

Mostly quartz/quartzite, feldspar-bearing granitoid, chert, and mafic volcanic rocks; exact species vary by pebble

Epidote-bearing Rock

Epidote / Silicate mineral aggregate

Turquoise

Hydrated copper and aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O)

Greenstone pebble (likely metamorphosed basalt)

Greenstone, commonly chlorite- and actinolite-bearing metabasalt

Rounded pebble, likely greenstone or altered basalt

Likely chlorite- or epidote-altered basalt; identification is uncertain from the image alone

Unakite

Unakite (altered granitic rock)

Weathered iron-rich rock, possibly limonite-bearing sandstone or laterite

Limonite/goethite mixture (hydrated iron oxides), composition uncertain from image

Weathered sandstone pebble

Quartz-rich sandstone, likely ferruginous sandstone

Polished greenstone pebble

Greenstone (chlorite–epidote–actinolite-rich metamorphosed mafic rock)

Weathered sandstone or iron-stained mudstone

Clastic sedimentary rock, likely quartz-rich sandstone (SiO₂) with iron-oxide coatings

Greenish rock with white veins, possibly epidote or chlorite bearing rock with quartz/calcite veins

Altered mafic rock or Epidosite

Polished unakite pebble

Unakite: epidote–feldspar (commonly pink K-feldspar and green epidote), with quartz

Likely weathered sandstone or iron-rich volcanic rock

Indeterminate from photograph; probable ferruginous sandstone, possibly altered volcanic rock

Dark gray volcanic rock, probably andesite or basalt

Fine-grained mafic–intermediate volcanic rock; likely basalt (plagioclase ± pyroxene), possibly andesite

Vesicular basalt with secondary zeolite/mineral crusts

Basalt, chiefly plagioclase–pyroxene ± olivine; cavities partly filled by zeolites or calcite

Weathered gray metamorphic rock, likely slate or phyllite

Foliated metapelite; composition commonly quartz, mica, and chlorite

Quartz Vein in Greenstone

Silica-infilled metabasalt

Weathered greenish-brown rock, likely serpentinized ultramafic rock

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with olivine, pyroxene, magnetite, or carbonate

Weathered limestone

Calcite-rich limestone (CaCO₃), possibly fossiliferous

Wonderstone Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Mixed rough mineral specimens, likely quartz-bearing rocks

Probable quartz (SiO₂), with possible feldspar, iron oxides, and altered host rock

Brecciated quartz-rich rock, possibly silicified breccia

Silica-rich breccia; chiefly microcrystalline quartz (SiO₂), with possible calcite and iron-oxide staining

Greenstone pebble (likely altered basalt or serpentine)

Greenschist-facies mafic rock; commonly chlorite–actinolite–epidote ± serpentine

Unakite / Epidotized Granite

Metamorphic Granite (Epidote-Orthoclase-Quartz Rock)

Unakite

Altered Granite

Weathered reddish-brown rock fragment

Probably altered basalt or fine-grained volcanic rock; exact identification requires testing

Iron-rich metamorphic rock (probable limonite/goethite-bearing schist)

Quartz–mica schist with iron oxyhydroxides, chiefly goethite (FeO(OH)) and limonite (amorphous hydrated iron oxides)

Greenstone / altered basalt pebble

Metamorphosed or hydrothermally altered mafic rock; likely chlorite–actinolite basalt (greenstone)

Granite (likely weathered, pegmatitic granite)

Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Banded calcite (likely marble or calcite-rich limestone)

Calcite, CaCO₃; possibly calcitic marble

Porphyritic volcanic rock, likely andesite or rhyolite

Porphyritic andesite–rhyolite; chiefly plagioclase, quartz, and altered ferromagnesian minerals in a fine groundmass

Greenstone (Epidosite or Serpentinite)

Metabasalt / Epidote-Chlorite Schist

Polished yellow jasper

Jasper, microcrystalline quartz (SiO₂), commonly containing iron oxides and other silicates

Weathered volcanic rock, likely altered basalt/andesite

Fine-grained mafic to intermediate volcanic rock; possible chlorite–calcite alteration

Light-colored weathered rocks, possibly limestone or quartz-rich stone

Probable limestone/calcitic rock; exact identification is uncertain because strong flash overexposure obscures texture