Industrial Byproduct (Anthropogenic Material)

Polished black pebble, likely basalt

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Possible iron meteorite

Fe–Ni iron meteorite, possibly an ordinary chondrite or weathered iron-rich specimen

Tumbled yellow jasper or weathered quartz-rich rock

Microcrystalline quartz (SiO₂), likely jasper with iron-oxide staining and dark inclusions

Garnet, likely almandine–spessartine

Garnet-group nesosilicate; commonly almandine Fe₃Al₂(SiO₄)₃ or spessartine Mn₃Al₂(SiO₄)₃

Possible rough agate/chalcedony nodule

Microcrystalline quartz (SiO₂), likely chalcedony or agate

Fossil shell fragment, likely bivalve or brachiopod

Indeterminate fossilized mollusk/brachiopod; commonly calcite (CaCO₃)

Rounded gray-brown pebble

Indeterminate; likely weathered quartz-rich sandstone or fine-grained volcanic rock

Raw green chalcedony (likely chrysoprase or prehnite)

Microcrystalline quartz, SiO₂; possible prehnite, Ca₂Al₂Si₃O₁₀(OH)₂

Fossil brachiopod in limestone

Brachiopoda; commonly a spiriferid or strophomenid brachiopod preserved in calcite-rich limestone

Tumbled brown stone, possibly jasper or iron-rich quartz

Uncertain; likely microcrystalline quartz (SiO₂) with iron-oxide inclusions

Sandstone with Iron Staining

Arenite (SiO2 with FeO(OH) impurities)

Garnet (Rough Almandine Crystal)

Almandine Garnet (Fe3Al2(SiO4)3)

Chalcedony

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Tumbled blue sodalite (probable)

Sodalite, Na₈(Al₆Si₆O₂₄)Cl₂

Conglomeratic breccia

Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix

Quartz geode (likely amethyst-bearing)

Silica geode; quartz, SiO₂, with possible amethyst and minor iron oxides

Sandstone (Quartzose)

Arenite (primarily SiO2)

Quartzite

SiO2 (Metamorphosed Sandstone)

Quartz Vein in Metamorphic Rock

Silicon Dioxide (SiO2) within Metasedimentary host

Sandstone (likely Quartzite-rich)

Arenite (primarily SiO2)

Sandstone

Arenite (primarily SiO2)

Schist (with Iron Oxide)

Mica Schist

Polished tiger’s-eye

Quartz variety, SiO₂, with crocidolite-derived iron inclusions

Quartz-rich breccia or quartz vein fragment

Silica, primarily quartz (SiO₂), with possible chlorite, feldspar, or iron-oxide inclusions

Milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled blue-dyed stone, likely basalt or blue aventurine

Likely fine-grained basalt (plagioclase and pyroxene), possibly coated or dyed; exact identification requires testing

Possible iron-rich basalt or industrial slag

Basalt, likely Fe–Mg silicate rock; exact identification is uncertain from the blurred image

Yellow faceted gemstone, likely citrine or synthetic glass

Citrine (quartz, SiO₂) is the leading natural possibility; visual identification is uncertain from the photograph

Diamond (in jewelry setting)

Cubic Carbon (C)

Quartzite

Quartzite (chiefly SiO2)

Quartz Pebbles

Silicon Dioxide (SiO2)

Iron-rich quartz specimen (likely hematite/goethite-coated quartz)

Quartz (SiO₂) with iron oxides, chiefly hematite (Fe₂O₃) and/or goethite (FeO(OH)); precise identification requires testing

Serpentine-rich rock (possibly lizardite/serpentinite)

Serpentinite, composed chiefly of serpentine-group minerals such as lizardite, antigorite, or chrysotile

Tumbled chert or siliceous river pebble

Microcrystalline quartz (SiO₂), likely chert with possible fossil or weathering cavities

Quartz geode (druzy quartz cavity)

Silica, SiO₂; microcrystalline-to-crystalline quartz lining a volcanic vesicle

Tumbled amber-colored chalcedony

Chalcedony (microcrystalline quartz, SiO₂), possibly yellow jasper or resinous amber-colored agate

Quartz geode/drusy quartz cluster

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

Chrysoprase-bearing quartz specimen (tentative)

Quartz (SiO₂) with nickel-bearing chalcedony/chrysoprase, possibly associated with host rock

Polished brown jasper pebble

Jasper, microcrystalline quartz (SiO₂) with iron-oxide impurities

Tumbled howlite (likely)

Howlite, Ca₂B₅SiO₉(OH)₅

Weathered quartz-rich nodule, possibly agate or chalcedony

Microcrystalline quartz (SiO₂), potentially with iron-oxide staining or a druzy coating

Rhodonite-bearing metamorphic rock

Rhodonite (MnSiO₃) with quartz and dark manganese oxides, likely a manganiferous schist or breccia