Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)

Pink Granite

Phaneritic Quartz-Feldspar Plutonic Rock

Quartz Geode/Vug in Host Rock

SiO2 (Silicon Dioxide) in various host rocks

Quartz geode fragment

Microcrystalline quartz (SiO₂), possibly with iron-oxide staining or an unidentified dark mineral inclusion

Quartz Geode with Calcite/Siderite

Crystalline Silicon Dioxide (SiO2) with Carbonate inclusions

Geode (unopened)

Quartz-filled Geode (SiO2)

Amethyst Geode

Silicon Dioxide (SiO2) with iron impurities

Weathered gray stone, possibly limestone or concrete-like carbonate rock

Tentatively micritic limestone (calcium carbonate, CaCO₃); exact identification is uncertain from the image

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Basalt

Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Quartz-rich translucent fragment

Quartz, silicon dioxide (SiO₂), possibly chalcedony or vein quartz

Botryoidal Hematite (Iron Stone Conglomerate)

Hematite (Fe2O3) in sedimentary matrix

Chalcedony (Agate/Quartz)

Silicon Dioxide (SiO2)

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich ironstone; chiefly hydrated iron oxides (FeO(OH)·nH₂O)

Ocean Jasper

Spherulitic Chalcedony (SiO2)

Septarian Nodule

Septarian concretion (Calcite, Aragonite, and Limestone)

Geode-like quartz vein in banded chalcedony

Quartz and chalcedony (SiO₂), possibly agate

Tumbled cream-colored stone, possibly calcite or quartz

Uncertain from image; likely calcite (CaCO₃) or milky quartz (SiO₂)

Quartz Geode

Silicon Dioxide (SiO2)

Calcite Geode

Calcium Carbonate (CaCO3)

Basalt

Basalt (Composition primarily Plagioclase feldspar, Pyroxene, and Olivine)

Quartz Geode (Cracked Open)

Quartz (Silicon Dioxide - SiO2)

Banded Agate with Drusy Quartz

Cryptocrystalline Quartz (SiO2) with macrocrystalline Quartz

Pink granite or granitic gneiss

Coarse-grained quartz–feldspar–mica rock; likely granite, possibly weathered gneiss

Basalt with Amygdaloidal Inclusions

Aphanitic Mafic Volcanic Rock (Basalt)

Limonite Concretion (Ironstone)

Limonite (FeO(OH)·nH2O) / Goethite

Quartz geode half

Quartz (SiO₂), likely a druzy quartz-lined geode

Quartz Geode

Silicon Dioxide (SiO2) in a Geode body

Chert Concretion (Flint)

Silicon Dioxide (SiO2)

Likely iron-rich concretion or weathered ironstone

Ironstone concretion, composed mainly of iron oxides/hydroxides (goethite and/or limonite) cementing sediment

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Moqui Marble

Hematite Concretion (Iron Oxide Concretion)

Fossilized Nut / Coprolite / Concretion

Trace Fossil / Permineralized Plant Material

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Ironstone Concretion (Limonite/Goethite)

Iron-rich sedimentary rock (FeOx)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Quartz with Calcite

Silicon Dioxide (SiO2) / Calcium Carbonate (CaCO3)

Quartz Geodes and Crystal Clusters

Silicon Dioxide (SiO2)

Weathered limestone or calcareous sandstone

Calcite-rich carbonate rock, predominantly CaCO₃; possibly fossiliferous limestone

Limonite (Ironstone Concretion)

Limonite (FeO(OH)·nH2O)

Amethyst geode or druzy quartz specimen

Quartz, SiO₂; purple coloration is typically caused by iron-related defects and irradiation

Weathered iron-rich concretion or sedimentary rock

Likely ferruginous sandstone or ironstone concretion; exact identification is not possible from the image alone

Quartz Geode in Chert/Limestone Matrix

Silicon Dioxide (SiO2) within Sedimentary Host Rock