Not A Geological Specimen

Quartz-Veined Porphyritic Basalt

Igneous rock with quartz vein (SiO2)

Polished black stone, possibly black jasper or obsidian

Uncertain; candidates include microcrystalline quartz (SiO₂; black jasper) or volcanic glass (obsidian, SiO₂)

Green cabochon gemstone, likely aventurine or dyed chalcedony

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

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Aura Quartz (Titanium/Rainbow Quartz)

SiO2 (Silicon Dioxide) with metallic coating

Colorless faceted gemstone, likely cubic zirconia

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

Limonite Geode / Ironstone Concretion

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

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

Veined Quartzite Pebble

Metamorphosed quartz sandstone

Mixed collection of polished geological specimens; central specimen is likely diorite

Diorite (probable; plagioclase feldspar and dark amphibole/biotite)

Fossilized Echinoid

Echinoidea

Vein-filled Basalt

Plagioclase-pyroxene volcanic rock with calcite veins

Conglomerate

Lithified, poorly sorted gravel; likely a carbonate-cemented conglomerate

Jasper Veined Quartzite

Metamorphosed quartz sandstone with iron oxide vein (SiO2)

Concrete / Anthropogenic Conglomerate

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

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Vein Quartz in Host Rock

Silicon Dioxide (SiO2) vein in sedimentary/metamorphic matrix

Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins

Quartz-veined metamorphic rock (Silicate mineral assemblage)

Chert with Asphaltum (or Tar)

Silica (SiO2) with natural Bitumen/Asphaltum

Quartz Vein in Host Rock

Silicified matrix with hydrothermal quartz (SiO2)

Quartz-veined rock

Silicate rock with quartz vein (SiO2)

Limonite Concretion

Hydrated Iron Oxide-Hydroxide (FeO(OH)·n H₂O)

Basalt with Jasper Vein

Extrusive Igneous Rock with Quartz/Chalcedony Vein

Exposed aggregate concrete (stone-chip surface)

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

Limonite (Ironstone Concretion)

Limonite (FeO(OH)·nH2O)

Pumice

Pumice (Vesicular Felsic Igneous Rock)

Porphyritic Basalt

Porphyritic Basalt with Olivine phenocrysts

Small weathered mineral/rock fragment

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

Quartzite Pebble (River Pebble)

Quartzite (SiO2)

Quartz Vein in Metamorphic Rock

Quartz-veined Schist or Gneiss

Quartz-veined Limestone

Sedimentary limestone with quartz/calcite veinlets

Concrete or asphalt-like aggregate surface with a dark fragment

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

Flint

SiO2 (Cryptocrystalline Quartz)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) vein cutting through host rock

Kite Stone

Porphyritic Lamprophyre

Ironstone / Weathered Hematite

Iron oxide-rich sedimentary rock with Goethite/Hematite

Quartz Veined Quartzite or Sandstone

Quartzite with Quartz Veins (SiO2)

Common Opal in Matrix

Hydrated amorphous silica (SiO2·nH2O)

Gneiss

Foliated quartz–feldspar gneiss, likely biotite-bearing

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode form

Polished brown stone, likely smoky quartz or jasper

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