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Carnelian

Carnelian (Microcrystalline Quartz, SiO2 with Fe2O3 impurities)

Ferruginous Sandstone

Sandstone, Iron-rich

Desert Rose

Gypsum (variety Selenite) or Barite, CaSO4·2H2O

Limonite (often after Hematite or Goethite)

Limonite (FeO(OH)·nH2O)

Gneiss

Gneiss (High-grade metamorphic rock)

Basalt

Mafic Igneous Rock (composed primarily of Pyroxene and Plagioclase Feldspar)

Granite

Phaneritic Granitoid (Primary minerals: Quartz SiO2, Feldspar KAlSi3O8, and Biotite/Mica)

Granite

Plutonic Igneous Rock (composed of Quartz, Feldspar, and Mica)

Carnelian

SiO2 (Silicon Dioxide) - Translucent Chalcedony

Carnelian

Carnelian (subset of Chalcedony); SiO2 with Iron Oxide impurities

Carnelian (a variety of Chalcedony)

SiO2 (Silicon Dioxide) primarily colored by iron oxide (Hematite)

Halite

Halite (Sodium Chloride - NaCl)

Diorite

Diorite (intermediate intrusive igneous rock)

Banded Agate (specifically Carnelian Agate / Sardonyx)

Silicon Dioxide (SiO2) with iron oxide inclusions

Red Scoria (Lava Rock)

Scoria (Vesicular Basalt/Andesite)

Granite

Granite (composed primarily of Quartz SiO2, Feldspar (KAlSi3O8), and Mica)

Biotite (Black Mica)

Biotite - K(Mg,Fe)3(AlSi3O10)(OH)2

Sandstone (Water-worn)

Arenite

Sandstone with Liesegang Rings

Arenite with secondary Iron oxide (Limonite/Goethite) precipitation

Carnelian Agate

Silicon Dioxide (SiO2) with Iron Oxide impurities

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 oxides)

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 cement)

Plagioclase Feldspar (specifically Albite/Oligoclase)

(Na,Ca)(Si,Al)4O8

Citrine Quartz

Crystalline Silicon Dioxide (SiO2) with Ferric Iron impurities

Sandstone (likely a river or beach pebble)

Sandstone (a clastic sedimentary rock)

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (Lithic arenite / Quartz arenite)

Sandstone (Picture Sandstone)

Sandstone (primarily Quartz with Iron Oxide impurities)

Limonite (also known as Yellow Ochre or Brown Hematite)

Limonite (Hydrated iron oxide-hydroxide, FeO(OH)·nH2O)

Granite with Quartz Vein

Phaneritic Felsic Igneous Rock (composed of Quartz [SiO2], Feldspar, and Mica)

Petrified Wood

Silicified Wood (primarily Silicon Dioxide, SiO2)

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Chalcedony in Limestone Host Rock

Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)

Anthracite Coal

Anthracite (Carbon Content: 86%-97%)

Banded Sandstone (Quartzite-rich)

Clastic Sedimentary Rock (SiO2 with Iron Oxide impurities)

Sandstone

Arenite (composed primarily of SiO2)

Granite

Phaneritic Felsic Igneous Rock (primarily SiO2, Al2O3, K2O, Na2O)

Amethyst

SiO2 (Silicon Dioxide)

Azurite and Malachite on Matrix

Azurite: Cu3(CO3)2(OH)2; Malachite: Cu2CO3(OH)2

Greenstone (Epidote/Chlorite-rich Metabasalt)

Greenschist / Epidosite (Ca2(Al,Fe)3(SiO4)3(OH))

Granodiorite

Granodiorite (containing Plagioclase, Quartz, and K-feldspar)