Sedimentary Rock (Metamorphosed)

Anthracite Coal

Anthracite (a variety of coal, predominantly carbon)

Mudstone

Argillite / Siliciclastic sedimentary rock

Slate

Slate (Metamorphic rock)

Banded Slate

Slate (Metamorphosed Siltstone/Mudstone)

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Sandstone (Quartzite-rich Pebble)

Arenite (primarily SiO2)

Banded Slate Pebble

Metamorphosed Mudstone / Slate

Zebra Jasper

Silicified sedimentary rock (SiO2) with mineral inclusions

Yellow Quartzite (River Pebble)

Quartzite (primarily SiO2)

Greenstone

Metamorphosed Mafic Igneous Rock

Quartzite

Metamorphosed Quartz Sandstone

River Cobbles (Quartzite and Sandstone)

Metamorphosed Quartz-rich Sedimentary Rock

Claystone / Mudstone

Mudstone (Hydrous aluminum silicate rich rock)

Brown quartz-rich pebble (likely chert or weathered quartzite)

Quartz (SiO₂), possibly microcrystalline quartz/chert or quartzite

Rounded gray pebble

Uncertain; likely quartz-rich sandstone, quartzite, or graywacke

River Stone (Quartzite/Chert)

Metamorphosed Quartz-rich Sedimentary Rock

Marble (White)

Metamorphosed Limestone (mainly CaCO3)

Blue Kyanite

Kyanite (Al2SiO5)

Quartzite (River Pebble)

Metamorphosed Sandstone (SiO2)

Rounded river or beach pebble

Likely quartz-rich sandstone or quartzite; exact identification requires a close-grained view and hardness test

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

River Rocks (Black)

Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts

Shatter Cone (Impactite)

Shock-metamorphosed rock

Gneiss (Metamorphosed Granitic Rock)

Gneiss (composed mainly of quartz, feldspar, biotite, and/or hornblende)

Quartzite with Chert inclusions

Metamorphosed Quartz-rich Rock (SiO2)

Likely graphite-rich schist

Graphitic schist; chiefly graphite and quartz/mica

Blue Apatite

Fluorapatite / Apatite group (Ca5(PO4)3(F,Cl,OH))

Quartzite River Rock

Quartzite ($SiO_2$)

Rounded gray stone, likely slate or fine-grained sandstone

Probable slate (low-grade metamorphosed shale) or lithic sandstone; exact identification requires testing

Epidote with Quartz/Feldspar

Epidote (Ca2(Al, Fe)3(SiO4)3(OH)) with associated minerals in a host rock

Rounded white pebble, likely quartz-rich rock

Most consistent with quartzite or milky-quartz pebble; exact identification requires testing

Weathered brown rock fragment (likely sandstone or iron-stained quartzite)

Indeterminate; probable quartz-rich sandstone, SiO₂-dominated

Quartzite with Hematite staining

Metamorphosed Quartz Sandstone (SiO2)

Greenstone, likely altered basalt

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

Veined Limestone (or Quartz-Veined Slate/Shale)

Metamorphosed Sedimentary Rock with Calcite/Quartz Veins

Weathered sulfide-bearing metamorphic rock (probable pyrite schist)

Quartz–mica schist with iron sulfides, chiefly pyrite (FeS₂), possibly chalcopyrite (CuFeS₂)

Garnet Schist

Almandine Garnet in Micaceous Schist

Red Jasper

Silicon Dioxide (SiO2) mixture

Iron-stained quartz-rich rock, likely quartzite or silicified sandstone

Quartz (SiO₂) with iron-oxide minerals, chiefly hematite/goethite; exact host-rock identification is uncertain from the photograph

Riverstone (likely Gray Slate or Siltstone)

Metamorphosed fine-grained sedimentary rock (Argillite/Slate)

Sandstone (Quartzite Pebble)

Arenite / Metamorphosed Sandstone (SiO2)

Raw graphite-rich metamorphic rock (probable graphite schist)

Graphite schist; predominantly crystalline carbon (graphite, C) with mica and quartz