Industrial Byproduct (Anthropogenic Rock Like Material)

Vesicular basalt (likely scoria)

Basaltic scoria; predominantly plagioclase, pyroxene, and olivine in a mafic volcanic glass/microcrystalline matrix

Rounded pale pebble, likely limestone

Calcite-rich limestone (CaCO₃), identification tentative from appearance

Sandstone

Arenite (SiO2 with various cementing minerals)

Sandstone (Banded)

Clastic Sedimentary Rock (composed of SiO2, CaCO3, or Fe2O3 cement)

Iron-stained weathered stone (tentative)

Undetermined; possibly weathered iron-rich basalt or concretion

Pegmatite

Igneous Pegmatite

Likely metallic meteorite fragment

Unclassified iron-rich meteorite candidate; possible iron meteorite or stony-iron specimen

Quartzite

Quartzite (primarily SiO2)

Limonite (Iron Ore)

Limonite (mixture of hydrated iron(III) oxide-hydroxides)

Schist

Mica Schist

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) vein cutting through host rock

Banded Sandstone (Differential Weathering)

Clastic Sedimentary Rock (primarily SiO2)

Weathered iron-rich rock, possibly limonite/goethite-bearing breccia

Hydrated iron oxides/hydroxides, mainly limonite (mixture) and goethite, FeO(OH)·nH₂O

Chert (Flint)

Chert (SiO2)

Obsidian Arrowhead

Volcanic Glass (Primary composition: SiO2)

Pumice

Pumice (volcanic glass froth)

Epidote-bearing Rock / Epidote Inclusion

Epidote (Ca2(Al, Fe)3(SiO4)3(OH)) in host rock

Shale

Shale (claystone/mudstone)

Sandstone (likely Quartzose)

Arenite (primarily SiO2)

Anthracite Coal

Anthracite (Carbon-based organic sedimentary rock transitioned to metamorphic)

Banded Gneiss

Gneiss (Metamorphic rock)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Quartzite

Quartzite (SiO2)

Iron-stained quartz-rich pebble

Likely quartz with iron-oxide staining; exact identification is uncertain from the image

Slate

Foliated Metamorphic Rock

Raw amethyst quartz crystal

Quartz, silicon dioxide (SiO₂), purple variety amethyst

Sandstone

Clastic sedimentary rock (primarily SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Tumbled green aventurine (probable)

Quartz (SiO₂), commonly with fuchsite mica inclusions

Serpentine

Serpentine subgroup (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Weathered rock pebble, possibly quartz-rich sandstone

Uncertain from the image; likely quartz-bearing sandstone with iron-oxide staining

Sandstone (Ferruginous)

Arenite (with Iron Oxide)

Gray chalcedony (common agate/jasper fragment)

Microcrystalline quartz, SiO₂; likely chalcedony with weathered host-rock rind

Basalt

Basalt (Mafic igneous rock)

Small tumbled dark stone, possibly basalt or slag

Likely fine-grained basalt; exact identification is uncertain from the photograph

Red Sandstone

Arenite (primarily Quartz with Iron Oxide coating)

Garnet Schist

Almandine-Garnet Schist

Weathered iron-rich rock, possibly limonite-bearing basalt or ironstone

Undetermined; likely iron oxides/hydroxides (goethite–hematite–limonite) in a silicate host

Amethyst (likely synthetic or treated)

Purple quartz, SiO₂; color caused mainly by trace iron and irradiation

Serpentinite

Serpentinite (composed primarily of serpentine group minerals including antigorite, chrysotile, and lizardite)

Quartz geode/drusy quartz cluster

Quartz (SiO₂), with probable feldspar host and minor iron-oxide staining