Sedimentary Rock (Metamorphosed)

Puddingstone (specifically Michigan/Gowganda Puddingstone)

Quartzite Conglomerate (Gowganda Formation)

Biotite Mica

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

Slate

Foliated Metamorphic Rock (Slate)

Marble

Metamorphosed Limestone (calcite formulation CaCO3)

Iron-rich quartzite or weathered ironstone

Quartzite, chiefly SiO₂, with iron-oxide minerals such as hematite/goethite

Likely quartz-rich pebble (possibly weathered quartzite)

Quartzite; predominantly SiO₂ (identification tentative from photograph)

Quartzite (iron-stained, possibly metaconglomeratic)

Quartzite; predominantly recrystallized quartz (SiO₂) with iron-oxide accessory minerals

Rounded gray cobble, likely quartzite or fine-grained sandstone

Quartzite (SiO₂), provisional identification

Likely milky quartz-bearing rock

Quartz, silicon dioxide (SiO₂), possibly in a quartz-rich vein or sugary quartzite

Tumbled lapis lazuli

Lazurite-bearing calcite rock; lazurite approximately Na₃Ca(Si₃Al₃)O₁₂S

Greenstone

Metabasalt / Greenschist

Anthracite Coal

Anthracite

Zebra Jasper (Zebra Stone)

Tumbled Silicon Dioxide (SiO2) with impurities

Staurolite-bearing mica schist (probable)

Mica schist composed chiefly of muscovite/biotite, quartz, and likely staurolite or garnet

Iron-stained quartz/quartzite pebble

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

Weathered quartz-rich rock fragment

Indeterminate; possibly weathered granite, quartzite, or rhyolite

Unakite (or Epidote-rich Granite)

Unakite (Metamorphosed Granite consisting of Epidote, Orthoclase, and Quartz)

Biotite-rich granite or gneiss fragment

Dark mica-bearing granitoid; likely quartz–feldspar–biotite rock

Weathered quartz-rich rock, likely iron-stained quartzite

Quartzite; predominantly quartz (SiO₂) with iron-oxide coatings

Blue Quartzite (Dyed)

Metamorphosed Quartz-rich Sandstone (SiO2 with organic dye)

Dark granite or granitic gneiss

Granite; quartz + feldspar + biotite/hornblende, possibly weakly gneissic

Quartzite Pebble

Metamorphosed Quartz-rich Sandstone (SiO2)

Quartz-rich rock fragment

Likely milky quartz (SiO₂), possibly a pale quartzite fragment

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

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

Likely greenstone (serpentinized ultramafic rock)

Serpentinite, dominated by serpentine-group minerals (chrysotile/lizardite/antigorite), possibly with chlorite or epidote

Rounded brown pebble, likely chert or iron-stained quartzite

Chert (microcrystalline quartz, SiO₂) or quartzite (recrystallized quartz, SiO₂)

Tumbled sandstone or iron-stained quartzite pebble

Quartz-rich sandstone (SiO₂), possibly weakly metamorphosed quartzite

Weathered quartz-rich pebble, possibly granitic gneiss

Quartz–feldspar–mica aggregate; likely granitoid or gneiss

Weathered granite or granitic gneiss pebble

Granite, primarily quartz, feldspar, and mica; possibly weakly foliated gneiss

Dark slate or fine-grained metamorphic rock

Slate; chiefly fine-grained phyllosilicates, quartz, and feldspar

Limonitic Quartzite

Metamorphosed sandstone with Limonite (FeO(OH)·nH2O) staining

Quartz-rich limestone or calcitic marble

Calcite (CaCO₃), possibly with quartz (SiO₂)

Weathered gray rock fragment

Likely quartz-rich sandstone or weakly metamorphosed sandstone; exact identification is uncertain from the photograph

Rounded river pebble, likely quartz-rich sandstone or quartzite

Indeterminate quartz-rich clast; predominantly SiO₂

Rhodonite-bearing metamorphic rock

Manganese-rich metamorphic rock, chiefly rhodonite (MnSiO₃), with quartz and manganese oxides

Weathered granite or granitic gneiss

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

Banded iron formation fragment (likely hematite–magnetite ironstone)

BIF; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica as microcrystalline quartz (SiO₂)

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

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

Whetstone

Novaculite

Quartzite (with Iron Staining)

Metamorphosed Sandstone (mainly SiO2 with Fe2O3/FeOOH impurities)