Industrial Byproduct (Anthropogenic Material)

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

Small dark pebble, possibly basalt or iron-rich stone

Undetermined; image alone cannot confirm composition

Quartz Pebbles

Silicon Dioxide (SiO2)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered quartz-rich rock fragment

Indeterminate; likely quartz-bearing granitoid or quartzite

Cavansite on matrix

Cavansite, Ca(VO)Si₄O₁₀·4H₂O

Likely vesicular basalt (scoriaceous basalt)

Basalt, chiefly plagioclase feldspar, pyroxene, and commonly olivine; approximate composition 45–52% SiO₂

Green glassy slag (often sold as “sea glass” or “green obsidian”)

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Red synthetic corundum (ruby-colored lab-grown sapphire)

Corundum, aluminum oxide (Al₂O₃), likely synthetic and chromium-colored

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

Rounded river pebble, likely quartz-rich stone

Unidentified lithic clast; exact mineralogy cannot be determined from the image

Diamond

C (Carbon)

Chert (containing Flint nodules)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (often called Flint or Jasper)

Silicon Dioxide (SiO2)

Small tumbled jasper or agate pebble

Likely microcrystalline quartz (SiO₂), possibly jasper or chalcedony

Vesicular basalt (possibly slag-contaminated)

Basalt; chiefly plagioclase and pyroxene, with possible olivine and secondary minerals

Milky quartz

Quartz (silicon dioxide, SiO₂)

Clear quartz beads (likely rock crystal)

Quartz, silicon dioxide (SiO₂)

Small pale-gray stone, likely a water-worn quartzite or chert pebble

Undetermined; possibly quartzite (predominantly SiO₂)

Fossilized bivalve shell

Fossil Mollusca; likely a cemented or infaunal bivalve, possibly oyster or clam

Diamond

Carbon (C)

Diamond (in jewelry setting)

Cubic Carbon (C)

Tumbled chalcedony or agate

Microcrystalline quartz (SiO₂), likely pale agate/chalcedony

Probable metallic meteorite fragment

Unclassified iron meteorite candidate, chiefly kamacite (α-Fe–Ni alloy)

Tumbled rose quartz

Quartz, silicon dioxide (SiO₂), rose-colored variety

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

Tumbled milky quartz pebble

Quartz (SiO₂)

Milky quartz

Quartz, silicon dioxide (SiO₂)