Not A Geological Specimen

Concrete-like aggregate surface with embedded rock fragments

Anthropogenic concrete or exposed aggregate; not a natural rock specimen

Sandstone Concretion

Sedimentary Concretion (Quartz sand bound by mineral cement)

Concrete aggregate surface

Human-made cementitious composite; primarily calcium-silicate-hydrate cement with mixed silicate aggregate

Amygdaloidal Basalt (or Orbicular/Vesicular Basalt)

Basalt with quartz/agate amygdules

Mixed rock and mineral collection

Multiple specimens; visible pieces may include quartz, calcite, agate/chalcedony, jasper, and dyed or coated materials

Undetermined Due to Blur (Possible Flesh-Tone Mineral)

Unknown (Insufficient Visual Clarity)

Limonite

FeO(OH)•nH2O

Generic Rock Fragment

Rock Fragment

Riverstone (Sandstone Pebble)

Arenite (SiO2 with various lithic fragments)

Green cabochon gemstone, likely aventurine or dyed chalcedony

Indeterminate from image; possible quartz variety (SiO₂), including aventurine quartz or chalcedony

Limonite Geode / Ironstone Concretion

Hydrated iron oxide-hydroxide (FeO(OH)·n H2O)

Colorless faceted gemstone, likely cubic zirconia

Cubic zirconia (zirconium dioxide, ZrO₂); visual confirmation is unavailable

Aura Quartz (Titanium/Rainbow Quartz)

SiO2 (Silicon Dioxide) with metallic coating

Lightning Stone / Fulgurite-impregnated or Septarian-like Agate

Silicon dioxide (Quartz/Chalcedony) with host rock matrix

Quartz Vein in Basalt

Silica-infilled basaltic host rock

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Concrete / Anthropogenic Conglomerate

Man-made composite material (Portland cement, aggregate, and water)

Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins

Quartz-veined metamorphic rock (Silicate mineral assemblage)

Limonite (Ironstone Concretion)

Limonite (FeO(OH)·nH2O)

Chert with Asphaltum (or Tar)

Silica (SiO2) with natural Bitumen/Asphaltum

Quartz Vein in Metamorphic Rock

Quartz-veined Schist or Gneiss

Exposed aggregate concrete (stone-chip surface)

Portland-cement concrete containing natural aggregate; not a natural rock

Basalt with Jasper Vein

Extrusive Igneous Rock with Quartz/Chalcedony Vein

Small weathered mineral/rock fragment

Indeterminate; possibly quartz-bearing feldspathic rock or calcite-rich specimen

Porphyritic Basalt

Porphyritic Basalt with Olivine phenocrysts

Pumice

Pumice (Vesicular Felsic Igneous Rock)

Quartzite Pebble (River Pebble)

Quartzite (SiO2)

Ironstone / Weathered Hematite

Iron oxide-rich sedimentary rock with Goethite/Hematite

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) vein cutting through host rock

Concrete or asphalt-like aggregate surface with a dark fragment

Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock

Quartz-veined Limestone

Sedimentary limestone with quartz/calcite veinlets

Quartz Veined Quartzite or Sandstone

Quartzite with Quartz Veins (SiO2)

Polished brown stone, likely smoky quartz or jasper

Tentatively quartz (SiO₂), possibly smoky quartz; exact identification requires testing

Decorative polished pebbles

Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Granite River Pebble

Granite (Phaneritic Igneous Rock)

Ironstone / Hematite Concretion

Iron oxide / Fe2O3

Waterworn Pebble / Quartzite

Metamorphic/Sedimentary rock fragment

Fossilized Brain Coral

Diploria labyrinthiformis (Fossilized)

Mixed rock and mineral collection

Multiple specimens; visible examples may include quartz (SiO₂), amethyst (quartz), calcite (CaCO₃), and dark mafic rocks

Limonite/Goethite Iron Concretion

Hydrated iron oxide-hydroxide mixture (FeO(OH)·nH2O)

Blue Schist / Lydian Stone / Chert with Glaucophane

Metamorphic rock containing quartz and glaucophane