Anthropogenic Sedimentary (Man Made)

Chert (Flint/Jasper variety)

Microcrystalline Quartz (SiO2)

Slag (Industrial Glass)

Anthropogenic Vitreous Slag (Post-industrial byproduct)

Cobalt Blue Slag Glass

Amorphous Silicon Dioxide (anthropogenic) with Cobalt additives

Coquina

Bioclastic Limestone

Exposed aggregate concrete (stone-chip surface)

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

Possible basaltic volcanic rock or iron-rich meteorite

Likely basalt (plagioclase–pyroxene rock); meteorite status cannot be confirmed visually

Possible tektite or iron-rich slag-like natural specimen

Uncertain; possibly natural glass (tektite) or magnetite-rich rock

Sandstone

Arenite (with iron oxide cement)

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Sandstone

Arenite

Weathered concrete or cementitious slab (not natural rock)

Artificial calcium-silicate cement composite; likely Portland cement concrete

Sandstone

Arenite (primarily SiO2)

Chert

Microcrystalline Quartz (SiO2)

Sandstone

Arenite

Chert (Flint)

Silicon dioxide (SiO2)

Weathered chert or chalcedony nodule

Microcrystalline quartz (SiO₂), possibly silicified limestone or agate-like chalcedony

Blue slag glass or dyed glass-like industrial material

Amorphous silicate glass; likely copper-bearing blue slag, but possibly colored man-made glass

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Sandstone (Quartzose)

Arenite (composed primarily of SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Flint

SiO2 (Cryptocrystalline Quartz)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone

Arenite

Greenstone Celt (Polished Stone Axe)

Metamorphosed mafic rock (often Basalt or Diabase)

Belemnoit (Fossil)

Belemnoidea (Order), Rostrum / Guard

Sandstone

Arenite (SiO2 based)

Chert (White Chert/Flint)

Microcrystalline Quartz (SiO2)

Sandstone

Arenite (SiO2 based clastic rock)

Limpets Shell / Fossil Specimen

Patellogastropoda (Class)

Native Silver

Silver (elemental Ag)

Fossil Coral

Scleractinia (Stony Coral) fossil

Nickel coin (U.S. currency)

Cupronickel (75% Copper, 25% Nickel alloy)

Sandstone

Arenite (composed primarily of SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Limestone Pebble

Sedimentary Calcium Carbonate (CaCO3)

Chert (Flint)

Silicon Dioxide (SiO2)

Fossilized Coral (Coquina/Limestone)

Cnidaria Anthozoa (Fossilized)

Chert (Flint / Jasper)

Silicon Dioxide (SiO2)

Gypsum (Satin Spar / Alabaster variety)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Coquina

Bioclastic Limestone (composed primarily of CaCO3)

Chert (variations include Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)