Rock (Likely Sedimentary)

Weathered porphyritic volcanic rock (likely andesite or basalt)

Aphanitic to porphyritic andesite–basalt; composition commonly plagioclase, pyroxene, and minor iron oxides

Granite Pebble

Granite (Felsic Plutonic Rock)

Quartz-rich metamorphic rock, likely quartzite

Quartzite; predominantly microcrystalline to granular SiO₂, possibly with mica and feldspar

Porphyritic volcanic rock, likely andesite

Porphyritic andesite; mainly plagioclase, pyroxene/amphibole, and volcanic groundmass

Coal (most likely Bituminous or Anthracite)

Bituminous Coal (Grade of Coal), Anthracite (Grade of Coal)

Coal (most likely Bituminous or Anthracite)

Coal (primarily composed of carbon with varying amounts of other elements)

Basalt with Oxidized Inclusions

Extrusive Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Granite Pebble

Granite (Phaneritic Quartz-Feldspar intrusive rock)

Quartz–feldspar–mica metamorphic rock, likely gneiss

Gneiss; composition commonly quartz (SiO₂), feldspars, biotite/hornblende, and minor accessory minerals

Vesicular volcanic rock, likely scoria

Scoria; composition commonly basaltic to andesitic, rich in plagioclase and pyroxene

Granite

Phaneritic Felsic Igneous Rock

Sandstone or Siltstone

Arenite (if sandstone)

Milky Quartz/Clear Quartz Cluster

Silicon Dioxide (SiO2)

Dark fine-grained rock, likely basalt

Basalt; chiefly plagioclase feldspar and pyroxene, commonly with olivine and iron oxides

Coarse-grained granite or granitic pegmatite

Granite; primarily quartz (SiO₂), feldspar, and mica/amphibole

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Colorless faceted gemstone (likely cubic zirconia)

Cubic zirconia, zirconium dioxide (ZrO₂); possibly synthetic quartz or glass imitation

Dark vesicular volcanic rock, likely basaltic scoria

Scoria (vesicular basalt; composition commonly plagioclase, pyroxene, and iron-rich glass)

Feldspar-Quartz Rock (likely Pegmatite or Granite)

Feldspar-Quartz composite rock (KAlSi3O8 - SiO2)

Shale

Shale (Fine-grained clastic sedimentary rock)

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with fossil inclusions

Yellow Calcite

Calcium Carbonate (CaCO3)

Epidosite with Quartz (Unakite-variant or Jasper)

Epidotized Metasomatite

Blue Agate Geode Slice

Silicon Dioxide (SiO2) - Chalcedony variety

Vesicular volcanic rock, likely pumice or scoria

Pumice (highly vesicular rhyolitic–dacitic volcanic glass) or scoria (vesicular basaltic rock)

Granite

Intrusive igneous rock (Granite)

Quartz Pebble

Silicon Dioxide (SiO2)

Likely basalt

Basalt; fine-grained mafic volcanic rock, chiefly plagioclase and pyroxene with possible olivine

Likely basalt

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, clinopyroxene, and often olivine

Basalt (Weathered)

Mafic Igneous Rock

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Weathered granite-like rock

Coarse-grained granitic rock, likely quartz–feldspar–mica aggregate

Chert Pebble

Microcrystalline Quartz (SiO2)

Weathered quartz-rich river cobble, possibly quartzite

Quartzite (mostly microcrystalline SiO₂), tentatively identified

Tumbled epidote-bearing rock (likely epidote–quartz–feldspar aggregate)

Epidote-rich metamorphic rock; minerals likely epidote (Ca₂(Al,Fe)₃Si₃O₁₂(OH), quartz, feldspar, and dark amphibole/biotite)

Tumbled dark pebble

Indeterminate; likely basalt or fine-grained dark metamorphic rock

Greenstone / Serpentinite

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

Chalcedony (Agate/Carnelian)

Cryptocrystalline Quartz (SiO2)

Dark volcanic rock, likely basalt

Basalt; fine-grained mafic silicate rock dominated by plagioclase and pyroxene, commonly with olivine

Dark volcanic rock, likely basalt

Basalt; predominantly plagioclase feldspar, pyroxene, and minor olivine or magnetite

Tumbled dark stone, likely basalt or basaltic rock

Fine-grained mafic igneous rock; commonly basalt, composed mainly of plagioclase and pyroxene with possible olivine