Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Chalcedony

Silicon dioxide (SiO2)

Dark ironstone concretion (probable)

Iron-oxide-rich sedimentary concretion, likely hematite/goethite cementing sand or clay

Small translucent mineral fragment, possibly calcite or quartz

Probable calcite (CaCO₃) or quartz (SiO₂); image resolution prevents confident separation

Basalt

Basalt (Mafic Igneous Rock)

Weathered limestone or calcareous concretion

Calcite-rich carbonate rock; primarily calcium carbonate (CaCO₃), commonly calcite

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Fossil Coral

Hexagonaria or Rugose Coral (Fossilized Calcium Carbonate / Silica)

Quartz Druze

Silicon Dioxide (SiO2)

Ironstone Concretion (Moqui Marble)

Iron Oxide Concretion (Fe2O3 / FeO(OH) mixed with SiO2)

Ironstone Concretion

Siderite or Hematite Concretion

Ironstone Concretion / Hematite Nodules

Ferruginous Sedimentary Rock (primarily Hematite Fe2O3 and Goethite FeO(OH))

Dark gray fine-grained rock fragment

Likely basalt (possibly andesite); exact identification is limited by the photograph

Quartz geode fragment

Microcrystalline and crystalline silica, SiO₂; likely quartz-lined chalcedony geode

Clear Quartz Crystal

Quartz (Silicon Dioxide - SiO2)

Geode (Chert or Quartz Nodule)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon dioxide (SiO2)

Concrete or artificial stone core sample

Artificial conglomerate

Dyed Agate

Silicon Dioxide (SiO2) with artificial pigment

Blue Chalcedony

Chalcedony (SiO2)

Septarian Nodule (Dragon Stone)

Septarian Concretion (CaCO3 with Calcite, Aragonite, and Limestone/Bentonite)

Quartz Geode

Silicon Dioxide (SiO2)

Carnelian (a variety of Chalcedony)

Silicon Dioxide (SiO2) with iron oxide impurities

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Basalt River Pebble

Aphanitic Mafic Basalt

Amethyst cluster

Amethyst, purple quartz (SiO₂)

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

Chert (Flint) River Pebble

Microcrystalline Quartz (SiO2)

Septarian Nodule

Septarian Concretion (CaCO3, CaMg(CO3)2, SiO2)

Agate (specifically, likely a geode slice or nodule)

Agate (a variety of Chalcedony, with chemical formula SiO2)

K2 Jasper (K2 Granite)

Azurite in Granite (Biotite Granite with Azurite inclusions)

Red Jasper

Jasper (Silica/Silicon Dioxide, SiO2 plus iron inclusions)

Ironstone Concretion

Ferruginous Siltstone/Ironstone (Fe2O3)

Ironstone Concretion

Siderite or Goethite Concretion

Sandstone (with ripple marks)

Arenite / Quartz Sandstone

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Basalt

Basalt

Wishing Stone (Basalt/Siltstone with Quartz/Calcite vein)

Carbonaceous Siltstone with Quartz (SiO2) or Calcite (CaCO3) vein

Druzy Quartz Geode (with Chalcedony)

Silicon Dioxide (SiO2)

Quartz / Chalcedony Geode Fragment

Silicon Dioxide (SiO2)

Weathered sandstone or arkosic sandstone

Clastic sandstone, likely quartz–feldspar-rich (arkose)

Amethyst (specifically Chevron Amethyst or Dream Amethyst)

Silicon Dioxide (SiO2) with iron impurities

Blue Chalcedony

Silicon Dioxide (SiO2) - Microcrystalline Quartz