Sedimentary Rock (Metamorphosed)

Weathered limestone or calcitic marble

Calcite-rich carbonate rock, chiefly CaCO₃; likely fossiliferous limestone, possibly weakly metamorphosed marble

Polished banded ironstone (likely magnetite-rich)

Banded iron formation (BIF), chiefly quartz/chert and magnetite (Fe₃O₄), possibly hematite (Fe₂O₃)

Quartz-rich quartzite or silicified stone

Quartzite; predominantly microcrystalline quartz (SiO₂), with minor iron-oxide staining and possible feldspar/clay impurities

Coarse-grained granite or granitic gneiss

Granite; chiefly quartz (SiO₂), feldspar, and dark mica/amphibole. Strong foliation could indicate granitic gneiss.

Shale

Laminated Mudstone (Shale)

Weathered quartz-bearing sandstone or quartzite

Quartzite (SiO₂-rich), possibly weakly metamorphosed sandstone

Rounded white pebble, likely quartzite or limestone

Probable quartzite (microcrystalline quartz, SiO₂) or calcitic limestone (CaCO₃)

Rounded brown pebble, likely chert or iron-stained quartzite

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

Likely serpentinite or serpentinized ultramafic rock

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and relict olivine/pyroxene

Rounded quartz-rich cobble, likely granite or granitic gneiss

Granite/granitic gneiss; mainly quartz, feldspar, and mica

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitic rock; possible biotite gneiss

Quartzite

Quartzite; predominantly recrystallized quartz (SiO₂)

Likely mafic metamorphic rock with sulfide mineralization

Probable amphibolite or hornblende–biotite schist, locally bearing pyrite/other sulfides

Milky quartz-rich vein rock (likely quartzite or silicified host rock)

Quartz, SiO₂; possibly quartzite with iron-oxide and minor feldspar/clay inclusions

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

Quartzite (SiO₂), possibly ferruginous sandstone

Green serpentine-rich stone

Serpentine-group minerals, chiefly antigorite/lizardite; possibly nephrite or chlorite-bearing rock

Tumbled dark quartzite or basalt pebble

Likely fine-grained basalt (plagioclase–pyroxene), though quartzite is possible from the image

Banded iron formation fragment

BIF: microcrystalline quartz (chert/jasper) with iron oxides and/or magnetite

Rounded quartz-rich pebble

Likely quartzite or quartz-rich sandstone; primarily silicon dioxide (SiO₂)

Puddingstone (specifically Michigan/Gowganda Puddingstone)

Quartzite Conglomerate (Gowganda Formation)

Rounded granite or granitic gneiss cobble

Granite/granitic gneiss, chiefly quartz, feldspar, and mica

Quartzite (iron-stained, possibly metaconglomeratic)

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

Weathered quartz-rich rock, likely quartzite

Quartzite (mostly microcrystalline SiO₂), possibly quartz-rich sandstone

Weathered quartz-rich rock fragment

Indeterminate; possibly weathered granite, quartzite, or rhyolite

Quartzite (river pebble) and Gabbro (crushed rock)

Quartzite (metamorphosed Quartz Sandstone, SiO2) and Gabbro (Plagioclase-Clinopyroxene rock)

Pyrite-bearing metamorphic rock, likely pyrite schist or pyrite-rich slate

Pyrite (FeS₂) in a foliated quartz–mica-rich host

Weathered quartz-rich rock, likely milky quartz/quartzite

Quartz (SiO₂); possibly quartzite if metamorphosed sandstone

Likely milky quartz-bearing rock

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

Anthracite Coal

Anthracite

Zebra Jasper (Zebra Stone)

Tumbled Silicon Dioxide (SiO2) with impurities

Graphite-bearing schist (probable)

Graphite–quartz–mica schist; chiefly graphite (C), quartz (SiO₂), and mica

Quartz-rich rock fragment

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

Hornblende-biotite schist (probable)

Amphibole–biotite schist; chiefly hornblende, biotite, plagioclase, and quartz

Serpentine-rich serpentinite

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and chromite

Staurolite-bearing mica schist (probable)

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

Gray metamorphic rock, likely slate or phyllite

Probably quartz–mica phyllite or fine-grained slate; exact identification requires testing

Tumbled brown quartzite pebble

Quartzite, composed predominantly of microcrystalline quartz (SiO₂)

Shale or Slaty Mudstone

Argillaceous sedimentary rock

Dark granite or granitic gneiss

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

Weathered iron-rich quartzite or sandstone pebble

Ferruginous quartzite; primarily quartz (SiO₂) with iron-oxide coatings

Tumbled sandstone or iron-stained quartzite pebble

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

Specular hematite-bearing metamorphic rock

Hematite (Fe₂O₃) in quartz-rich metamorphic host, possibly iron formation or quartzite