Sedimentary Rock (Metamorphosed)

Weathered granite or granitic gneiss

Granite; mainly quartz (SiO₂), feldspar, and mica, possibly with metamorphic foliation

Chlorite-rich schist (probable greenschist)

Greenschist-facies metabasalt or chlorite–actinolite schist

Serpentinite (likely serpentinized ultramafic rock)

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and relict olivine/pyroxene

Iron-stained quartz/quartzite pebble

Quartz (SiO₂), likely quartzite or quartz-rich vein rock with iron oxides

Whetstone

Novaculite

Tumbled quartz-rich pebble, possibly quartzite

Quartz (SiO₂), likely in a quartzite or siliceous rock matrix

Inscribed limestone fragment

Calcitic limestone (primarily CaCO₃), possibly marble if recrystallized

Rounded quartz-rich river pebble

Likely quartzite or quartz-rich sandstone; predominantly SiO₂

Rounded quartz-rich pebble

Likely quartzite or quartz-bearing sandstone with iron-oxide staining

Iron-stained quartzite or quartz-rich rock

Quartzite, predominantly SiO₂, colored by iron oxides (hematite/goethite)

Weathered biotite granite or granitic gneiss

Felsic granitoid, chiefly quartz, K-feldspar, plagioclase, and biotite; possible gneissic deformation

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly polycrystalline quartzite

Greenstone / altered basalt (likely serpentinite or chlorite-rich rock)

Chlorite–actinolite schist or weakly metamorphosed basalt; exact identification requires testing

Weathered quartz-rich pebble, possibly granitic gneiss

Quartz–feldspar–mica aggregate; likely granitoid or gneiss

Biotite-rich schist

Mica schist; predominantly biotite mica with quartz and feldspar

Possible chert or weathered quartzite fragment

Microcrystalline quartz (SiO₂), identification uncertain from the photograph

Weathered iron-rich metamorphic rock, likely banded ironstone or quartzite

Ferruginous quartzite/itabirite; mainly quartz (SiO₂) with iron oxides such as hematite and goethite

Weathered quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly quartz (SiO₂), possibly with feldspar, mica, and iron-oxide staining

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), potentially quartzite if metamorphic

Dark mafic rock, likely basalt or amphibolite

Probable basalt (plagioclase feldspar + pyroxene ± olivine); definitive identification requires a fresh surface or thin section

Biotite-rich schist

Mica schist; predominantly biotite mica (K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂), commonly with quartz and feldspar

Weathered biotite-rich schist (probable mica schist)

Mica schist, chiefly quartz + biotite mica; possible graphite or iron-oxide staining

Biotite-rich mica schist (tentative)

Mica schist, dominated by biotite; approximate formula K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂

Iron-stained quartz vein rock

Quartz-rich vein material with iron oxides/hydroxides (quartz, SiO₂, stained by hematite/goethite); likely hosted in a metamorphic rock

Iron-rich metamorphic rock (likely banded iron formation fragment)

Banded iron formation; chiefly quartz (SiO₂) and iron oxides such as hematite (Fe₂O₃) and magnetite (Fe₃O₄)

Likely biotite-rich metamorphic rock (mica schist)

Mica schist, chiefly quartz + biotite mica; possible pyrite or sulfide grains

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), likely with iron-oxide and chlorite/serpentine staining

Banded iron formation (iron-rich metamorphic rock)

Banded iron formation, typically hematite–magnetite–quartz (Fe₂O₃/Fe₃O₄/SiO₂)

Quartz-rich quartzite pebble

Quartzite (mostly SiO₂)

Greenstone with rusty mineral patches

Greenstone (metamorphosed mafic volcanic rock; likely chlorite–epidote–actinolite assemblage)

Iron-rich banded iron formation fragment (likely hematite/magnetite ore)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica (SiO₂)

Dragon blood jasper

Epidote- and piemontite-bearing quartz/chalcedony (trade name)

Iron-stained quartzite or quartz-rich rock

Quartzite; predominantly microcrystalline quartz (SiO₂) with iron-oxide staining

Granite or granitic gneiss gravel

Crystalline quartz–feldspar–mica aggregate; possibly weathered granitic gneiss

Honey-colored quartz-rich rock, possibly yellow chalcedony or quartzite

Quartz/chalcedony, SiO₂; exact identification is uncertain from the photograph

Anthracite coal

Anthracite; predominantly carbon (C), with minor macerals, ash, sulfur, and trace minerals

Weathered quartz-rich rock, possibly quartzite or silicified breccia

Quartzite (predominantly SiO₂); exact identification requires a fresh surface and tests

Weathered quartz-rich metamorphic rock

Likely quartzite or quartz-mica schist; predominantly SiO₂ quartz with possible feldspar and mica

Weathered iron-rich metamorphic rock, likely banded iron formation or ferruginous quartzite

Quartz–iron oxide rock; chiefly SiO₂ with hematite (Fe₂O₃), magnetite (Fe₃O₄), and minor limonite/goethite

Likely weathered granite or granitic gneiss

Granite: quartz + feldspar + mica; possibly gneiss if the faint banding is structural

Likely serpentinized ultramafic rock (serpentinite)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, possibly with magnetite, chromite, and brucite

Pink Marble (Quartzite or Calcite mix)

Metamorphosed Limestone / Quartzite (CaCO3 or SiO2 with iron impurities)