Rock (Likely Sedimentary)

Basalt with Epidote (Porphyritic Basalt)

Mafic Porphyritic Basalt with (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) inclusions

Copper-Bearing Sulfide Ore (likely Chalcopyrite or Bornite)

Chalcopyrite (CuFeS2) or Bornite (Cu5FeS4) in host rock

Porphyritic Basalt

Aphanitic-Porphyritic Basalt

Brown Agate

Silicon Dioxide (SiO2)

Sandstone (with Manganese staining)

Arenite (composed primarily of SiO2)

Quartz-rich granite or pegmatitic rock

Granite, composed mainly of quartz, feldspar, and mica; exact identification is uncertain from the photograph

Granite

Phaneritic plutonic igneous rock (typically 20% to 60% quartz by volume)

Cinnabar

Mercury(II) sulfide (HgS)

Quartzite

Quartzite (composed mainly of SiO2)

Granite pebble

Granite, chiefly quartz, feldspar, and mica

Quartzite river stone

Quartzite (SiO2)

Vesicular volcanic rock, likely pumice

Pumice; highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition

Garnet-bearing metamorphic rock, likely mica schist

Biotite–garnet schist; commonly includes quartz, feldspar, biotite, and almandine garnet

Dark green metamorphic rock, likely serpentinite

Serpentinite, composed mainly of serpentine-group minerals (antigorite, lizardite, or chrysotile), commonly with magnetite and minor chlorite/talc

Likely smoky quartz-bearing rock or quartz crystal

Quartz, silicon dioxide (SiO₂), possibly smoky quartz with iron- or irradiation-related coloration

Vesicular volcanic rock, likely pumice or scoria

Vesicular rhyolitic–andesitic volcanic rock; predominantly silicate glass with feldspar and possibly pyroxene

Tumbled quartz-rich rock, likely quartzite or milky quartz with iron-oxide staining

Quartzite (primarily SiO₂), possibly with hematite/goethite staining and minor feldspar or mica

Basalt with Quartz/Feldspar Inclusions

Amygdaloidal or Porphyritic Mafic Volcanic Rock with Siliceous Veining

Basalt (Weathered Pebble)

Extrusive mafic rock (primarily Plagioclase Feldspar and Pyroxene)

Quartzite Pebble

Quartzite (SiO2)

Quartzite

Quartzite (primarily SiO2)

Quartzite

Quartzite (SiO2 silicon dioxide)

Basalt Pebble

Extrusive Mafic Igneous Rock

Milky quartz with iron-oxide staining and dark matrix

Quartz (SiO₂), likely with hematite/goethite and minor feldspar or mica

Chert (Yellow Jasper)

Cryptocrystalline Quartz (SiO2)

Rounded quartz-rich cobble, likely granite-derived stone

Granite or granitic gneiss, composed mainly of quartz, feldspar, and minor mica

Granite Cobble

Granite

Limestone with Iron Inclusions

Calcium Carbonate (CaCO3) with Hematite/Limonite

Tumbled blue sodalite (probable)

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂; possibly lapis-lazuli if lazurite is present

Weathered porphyritic pebble

Likely porphyritic volcanic rock, possibly andesite or rhyolite

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Granite

Phaneritic plutonic rock (Quartz + Alkali Feldspar + Plagioclase Feldspar)

Biotite-rich granite or granitic gneiss

Quartz–feldspar–biotite granite; possibly foliated granitic gneiss

Agate

Chalcedony (Silicon Dioxide, SiO2)

Quartz (vein quartz)

SiO2 (Silicon Dioxide)

Basalt (Crushed Roadstone)

Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Basalt (Weathered/Tumbled)

Extrusive Mafic Igneous Rock

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Yellow Chalcedony (Agate/Jasper mix)

Silicon Dioxide (SiO2)

Corundum

Corundum (Al2O3)

Granite Cobble

Granite (Felsic Intrusive)

Conglomerate (Quartz Pebble Conglomerate)

Quartz Pebble Conglomerate