Sedimentary Rock (Metamorphosed)

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly polycrystalline quartzite

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂); possibly quartzite with iron-oxide staining

Rounded granitic gneiss or granite cobble

Quartz–feldspar–mica rock; likely granitoid, possibly weakly gneissic

Tumbled greenish stone, likely serpentinite or greenstone

Probable serpentine-rich ultramafic rock; exact identification requires testing

Weathered granite or granitic gneiss

Quartz–feldspar–mica granitic rock; possibly gneiss if foliation is present

Quartzite (or Ferruginous Quartzite)

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 impurities)

Likely weathered granite or granitic gneiss

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

Granite or granitic gneiss gravel

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

Rounded quartz-rich pebble

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

Weathered granite or granitic gneiss

Granite; chiefly quartz, feldspar, and mica/amphibole

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

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

Quartz-bearing iron-rich rock, possibly quartzite or hydrothermal breccia

Quartz (SiO₂) with iron oxides/hydroxides, likely limonite/goethite; exact host rock is uncertain from the photograph

Weathered quartz-rich rock, likely milky quartz/quartzite

Quartz (SiO₂); possibly quartzite if metamorphosed sandstone

Quartz and Slate Pebbles

Silicon Dioxide (SiO2) and Metamorphosed Shale/Mudstone

Iron-rich metamorphic rock, likely banded iron formation fragment

Hematite–magnetite-rich quartzite (BIF); Fe₂O₃/Fe₃O₄ with SiO₂

Weathered quartz-rich rock, likely quartzite

Quartzite; predominantly crystalline SiO₂, possibly iron-oxide stained

Likely serpentinized ultramafic rock (serpentinite)

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

Weathered quartz-rich rock, likely chert or quartzite

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

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with minor dark inclusions

Weathered quartz-rich rock, possibly quartzite

Quartzite; predominantly microcrystalline quartz (SiO₂)

Rounded gray river pebble, likely quartz-rich metamorphic rock

Probable quartzite or quartz-rich schist; exact identification is uncertain from the photograph

Likely mica-rich schist with embedded dark pebble

Biotite–quartz schist; dark clast possibly basalt or chert

Likely granite or granitic gneiss

Quartz–feldspar–mica aggregate; possibly foliated granitic gneiss

Quartzite (river pebble) and Gabbro (crushed rock)

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

Tumbled reddish-brown pebble, likely sandstone or iron-rich quartzite

Probable ferruginous sandstone (quartz-rich; SiO₂ with iron oxides), possibly quartzite

Synthetic Marbled Aggregate (Footwear Component)

Ethylene-vinyl acetate (Croslite™)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)

Shale

Shale (clastic sedimentary rock)

Tumbled quartzite pebble

Quartzite; predominantly microcrystalline quartz (SiO₂)

Weathered quartz-rich rock, likely quartzite or quartz vein fragment

Quartzite, composed predominantly of SiO₂; possible iron-oxide staining

Red granite or granitic gneiss pebble

Felsic granitoid, likely quartz–feldspar–biotite granite; possible weakly gneissic texture

Banded iron formation (likely iron-rich metamorphic rock)

Banded iron formation; hematite–magnetite with chert/jasper (Fe₂O₃/Fe₃O₄ and SiO₂)

Weathered feldspathic quartzite or granitic rock fragment

Quartz-rich silicate rock; exact identification requires thin-section or chemical testing

Tumbled quartz-rich rock, possibly jasperized quartz or quartzite

Quartz (SiO₂), likely with iron-oxide staining and minor feldspar or other silicate minerals; exact identification is uncertain from the photograph

Weathered quartz-rich rock, likely quartzite or altered sandstone

Quartzite (mostly microcrystalline quartz, SiO₂); exact identification is uncertain from the photograph

Weathered quartz-rich cobble (likely quartzite)

Quartzite; predominantly microcrystalline quartz (SiO₂)

Quartz-rich mica schist

Muscovite–quartz schist, with possible feldspar and iron-oxide staining

Shale

Laminated Mudstone (Shale)

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂); possibly quartzite, a recrystallized quartz sandstone

Banded iron formation (iron-rich metamorphic rock)

Banded iron formation, chiefly hematite/magnetite with chert or quartz (Fe₂O₃/Fe₃O₄ + SiO₂)

Weathered granite or granitic gneiss

Granite; primarily quartz, feldspar, and mica (possibly metamorphosed to gneiss)