Banded Agate (specifically Carnelian Agate / Sardonyx)
Silicon Dioxide (SiO2) with iron oxide inclusions
mineral
Category
Synthetic (Not A Natural Rock)
Browse synthetic (not a natural rock) specimens identified by the Rock Identifier community.
Sodalite
Sodalite, Na8(Al6Si6O24)Cl2
Mineral
Basalt (River Rock/Cobble)
Basalt (no specific mineral formula as it's a rock)
Igneous
Coral (Precious Coral)
Corallium rubrum (Red Coral), Paracorallium japonicum (Momo Coral), Pleurocorallium elatius (Sardinian Coral), various other species within the Corallidae family. Chemically, it's primarily Calcium Carbonate (CaCO 3 ).
Mineral, Organic Gemstone
Chert (specifically Gray/Tan Bedded Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Anthracite Coal
Anthracite (Carbon Content: 86%-97%)
metamorphic
Limestone with Weathering Rind
Calcium Carbonate (CaCO3) - Bioclastic or Micritic Limestone
sedimentary
Quartzite (Yellow/Iron-Stained)
Quartzite (SiO2 with Iron Oxide impurities)
metamorphic
Chert (specifically Yellow/Brown Chert or Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Bumblebee Jasper
Hydrothermal Volcanic Rock (Primarily Calcite with Orpiment - As2S3, Realgar, and Pyrite)
igneous
River Pebble (Gabbro or Basalt)
Mafic Igneous Rock (composed primarily of Pyroxene and Plagioclase Feldspar)
igneous
Schorl (Black Tourmaline) in Pegmatite
Sodium Iron Aluminum Borosilicate (NaFe3Al6(BO3)3Si6O18(OH)4)
igneous
Seraphinite
Clinochlore (a variety of the chlorite group)
mineral
Diamond (in Jewelry)
Carbon (C)
mineral
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
mineral
Hematite
Iron(III) oxide (Fe2O3)
Mineral
Celestite Geode
Celestine (Strontium Sulfate, SrSO4)
mineral
Granite
Phaneritic Plutonic Felsic Rock (primarily Quartz (SiO2), Alkali Feldspar, and Plagioclase Feldspar)
igneous
Dalmatian Stone (commonly called Dalmatian Jasper)
Peralkaline Rock (mixed Feldspar, Quartz, and Arfvedsonite)
igneous
Amethyst
SiO2 (Silicon Dioxide)
Mineral
Banded Agate with Druzy Quartz
Agate (Silicon Dioxide - SiO2)
mineral
Quartz (Milky or Rough Quartz)
Silicon Dioxide (SiO2)
mineral
Gneiss
Gneiss (High-grade regional metamorphic rock)
metamorphic
Magnetite
Magnetite (Fe3O4)
Mineral
Ruby in Zoisite
Ruby (α-Al2O3) embedded in Zoisite (Ca2Al3(SiO4)3(OH)) with some Hornblende
Metamorphic Rock (composed of multiple minerals)
Fluorite (Rainbow or Multi-colored Fluorite)
Fluorite (Calcium Fluoride - CaF2)
mineral
Marble
Metamorphosed Limestone (principally CaCO3)
metamorphic
Turquoise
Hydrated phosphate of copper and aluminium, CuAl6(PO4)4(OH)8·4H2O
mineral
Limonite (after Pyrite Pseudomorph)
Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)
mineral
Ferruginous Breccia
Breccia with Iron-rich (Hematite/Goethite) Matrix
sedimentary
Amethyst
SiO2 (Silicon Dioxide)
Mineral
Amethyst Geode
Silicon Dioxide (SiO2) with trace Iron (Fe3+) impurities
mineral
André Landed Here Rock (Glacial Erratic)
Granodiorite / Diorite (compositional estimate)
igneous
Red Granite
Phaneritic Plutonic Rock (High Potassium Feldspar)
igneous
Black Onyx
Black Chalcedony (SiO2)
mineral
Rough Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
metamorphic
River Rocks (Black)
Various lithologies (e.g., basalt, chert, obsidian for black varieties), mechanically rounded clasts
Sedimentary
Quartzite (Yellow/Orange variety)
Quartzite (composed primarily of Silica, SiO2)
metamorphic
Amber
Fossilized Tree Resin (C10H16O)
mineral
Quartzite (River Cobble)
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Amethyst
SiO2 (Silicon Dioxide)
Mineral