Organic Specimen (Fossil)

Ironstone Concretion

Ferruginous Sandstone / Siderite Concretion

Shale (possibly Carbonaceous or Oil Shale)

Argillaceous Sedimentary Rock

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Fossilized Brachiopod/Bivalve in Limestone

Brachiopoda or Bivalvia fossil in Calcite/Limestone (CaCO3)

Travertine / Tufa

Calcium Carbonate (CaCO3)

Chert Pebble

Microcrystalline or cryptocrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Chert (containing fossil leaf impression)

Microcrystalline silicon dioxide (SiO2)

Rounded limestone pebble

Limestone, predominantly calcite (CaCO₃)

Fossiliferous Limestone

Calcareous Sedimentary Rock (CaCO3)

Lemon (Mock specimen mimicking Citrine/Sulfur)

Citrus x limon

Favosites Fossil (Honeycomb Coral Pebble)

Favosites goldfussi / Silicified Coral Fossil

Coal (specifically Bituminous or Anthracite)

Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N

Amber

Succinite (C10H16O)

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Calcite-rich limestone, possibly fossiliferous

Limestone composed mainly of calcite (CaCO₃), potentially containing a fragmentary fossil or calcite-filled structure

Amber

Succinite (specific to Baltic amber), fossilized tree resin

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone (Flagstone)

Arenite (composed primarily of SiO2)

Pale limestone

Limestone, predominantly calcite (CaCO₃)

Limestone (Travertine/Tufa variant)

Calcium Carbonate (CaCO3)

Limestone (specifically fossiliferous/skeletal limestone)

Calcium Carbonate (CaCO3)

Sandstone (with banding/weathering)

Clastic Sedimentary Rock (primarily SiO2)

Weathered agate or chalcedony nodule

Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining

Ironstone Concretion (Iron-rich Mudstone)

Siderite / Geothite concretion (FeCO3 / FeO(OH))

Vesicular volcanic rock, likely pumice or scoriaceous rhyolite

Vesicular rhyolite/dacite; predominantly silica-rich volcanic glass with feldspar and quartz

Chert (Jasper/Agate variant)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2 permineralization)

Fossiliferous Limestone (with Oyster Fossils)

Fossiliferous Calcarenite / Bivalve Mollusk Fossil

Sandstone (Weathered Cobble)

Clastic Sedimentary Rock (primarily SiO2)

Fossiliferous Sandstone with Plant Remains

Arenite with Carbonaceous impressions (likely Paleozoic/Mesozoic Flora)

Petrified Wood

Silicified wood (primarily Silicon Dioxide - SiO2)

Sandstone

Arenite (primarily composed of SiO2)

Petrified Wood

Silicified Wood (SiO2 - Silicon Dioxide)

Weathered sandstone or arkose fragment

Quartz-rich clastic sedimentary rock; likely sandstone/arkose (dominantly SiO₂ quartz with feldspar and lithic grains)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Chert (Arrowhead Artifact)

Chert (SiO2)

Amber

Succinicum (Organic polymer, largely C10H16O)

Chert (containing a small fossil)

Microcrystalline Quartz (SiO2)

Sandstone

Arenite (primary component SiO2)

Weathered limestone

Calcite-rich limestone (CaCO₃), possibly fossiliferous

Chert (variations include Flint)

Chert (Silicon Dioxide, SiO2)