Sedimentary Rock (Metamorphosed)

Likely gray sandstone or fine-grained metamorphic rock

Quartz-rich lithic sandstone; exact identification is uncertain from the photograph

Shatter Cone (Impactite)

Shock-metamorphosed rock

Rounded river or beach pebble

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

Gneiss (Metamorphosed Granitic Rock)

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

Blue Kyanite

Kyanite (Al2SiO5)

Quartzite River Rock

Quartzite ($SiO_2$)

Greenstone / Metagraywacke

Metamorphosed basaltic or sedimentary rock (Complex Silicate)

Likely garnet-bearing schist

Garnet mica schist; commonly quartz + mica (muscovite/biotite) ± garnet

River Rocks (Black)

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

Rounded pebble, likely sandstone or iron-stained quartzite

Unidentified clastic rock; composition cannot be determined from the image alone

Quartzite with Hematite staining

Metamorphosed Quartz Sandstone (SiO2)

Weathered quartz-rich rock, possibly quartzite or altered granite

Quartz-dominant silicate rock; exact identification requires a fresh surface and tests

Greenstone, likely altered basalt

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

Rounded gray stone, likely slate or fine-grained sandstone

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

Likely quartz-rich pebble fragment

Quartz (SiO₂), possibly milky quartz or quartzite; the photo is insufficient to distinguish them confidently

Rounded white pebble, likely quartz-rich rock

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

Rounded quartz-rich pebble

Likely quartzite or quartz-rich sandstone; predominantly SiO₂

Feldspar-rich granite or granitic gneiss

Granite; mainly quartz (SiO₂), feldspar, and mica

Black-and-white veined stone, likely marble or calcite-veined metamorphic rock

Probable calcite marble: predominantly recrystallized calcite (CaCO₃) with dark graphite-, mica-, or amphibole-rich minerals

Mica-rich schist (likely biotite schist)

Biotite schist; quartz- and feldspar-bearing, with abundant mica

Quartz-bearing metamorphic rock, possibly quartzite or hornfels

Mostly quartz (SiO₂), with probable iron-oxide and dark silicate minerals

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-veined schist; primarily SiO₂ with possible mica, feldspar, and iron oxides

Likely garnet-bearing schist

Mica schist, possibly garnet-bearing; exact identification requires closer examination

Quartz-rich rock, likely milky quartz with iron staining

Quartz (SiO₂), possibly quartzite or quartz vein material

Weathered quartz-rich metamorphic pebble

Likely quartzite or quartz-mica schist; identification is uncertain from the photograph

Likely graphite-rich schist

Graphitic schist; chiefly graphite and quartz/mica

Dark rock specimen (possibly slate or shale)

Unidentified fine-grained rock; slate is foliated metamorphosed shale, while shale is sedimentary mudrock

Sandstone (Quartzite Pebble)

Arenite / Metamorphosed Sandstone (SiO2)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Metallic sulfide-bearing metamorphic rock

Likely graphitic schist or sulfide-rich schist, with possible pyrite/arsenopyrite and mica

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

Indeterminate; probable quartz-rich sandstone, SiO₂-dominated

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂); if quartzite, recrystallized quartz sandstone

Quartzite with Quartz Vein

Metamorphosed Quartz-rich Sandstone (SiO2)

River Pebbles (Chert and Quartzite)

Sedimentary Clastic Rock (Silica-rich)

Weathered sulfide-bearing metamorphic rock (probable pyrite schist)

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

Rounded granitic gneiss or granite cobble

Likely biotite granite/granitic gneiss; quartz + feldspar + biotite/hornblende

Marble

Metamorphosed Limestone/Dolomite

Likely quartz-rich stone, possibly milky quartz

Quartz (silicon dioxide, SiO₂)

Likely muscovite mica schist

Muscovite-rich mica schist; muscovite KAl₂(AlSi₃O₁₀)(OH)₂

Banded slate or phyllite

Fine-grained foliated metasedimentary rock; likely slate with light-colored quartz veins

Biotite-bearing schist

Mica schist, chiefly quartz–feldspar–biotite (phyllosilicate-rich)

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