Dyed Agate (Tumbled)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Category
Sedimentary Rock (Specifically A Clastic Sedimentary Rock Formed Into A Cobble)
Browse sedimentary rock (specifically a clastic sedimentary rock formed into a cobble) specimens identified by the Rock Identifier community.
Anthracite Coal
Anthracite (Carbon-based organic sedimentary/metamorphic rock)
metamorphic
Quartz
Silicon Dioxide (SiO₂)
Mineral
Chert (specifically Flint or Common Opal)
Silicon Dioxide (SiO2)
sedimentary
Limonite Pseudomorph after Pyrite
Limonite (Hydrous iron oxides, FeO(OH)·nH2O) replacing Pyrite (FeS2)
mineral
Quartz (likely tumbled or naturally water-worn)
Quartz (SiO₂ - Silicon Dioxide)
Mineral
Banded Chert (or Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Ironstone Concretion / Limonite Node
Ferruginous Sedimentary Rock (composed primarily of Limonite FeO(OH)·nH2O and Goethite)
sedimentary
Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Chert (Jasper/Flint variety)
Microcrystalline Quartz (SiO2)
sedimentary
Fossilized Oyster Shell
Gryphaea or Crassostrea fossil (Calcium Carbonate, CaCO3)
sedimentary
Banded Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Travertine (Calcareous Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Gneiss
Gneiss (a type of metamorphic rock)
Metamorphic Rock
Quartz (Rock Crystal)
Quartz (SiO₂ - Silicon Dioxide)
Mineral
Fossilized Favosites (Honeycomb Coral)
Favosites (Genus), Phylum Cnidaria, Class Anthozoa
sedimentary
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
sedimentary
Chert (Tan/Yellow variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Red Granite
Phaneritic Felsic Intrusive Igneous Rock (primarily K-feldspar, Quartz, and Biotite)
igneous
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Chert (Nodule)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Black Jasper
Silicon Dioxide (SiO2) with Carbonaceous inclusions
sedimentary
Chert (specifically Flint or Gray Chert)
Silicon Dioxide (SiO2)
sedimentary
Dragon Blood Jasper
Epidote with Red Jasper inclusions (SiO2 and Ca2(Al,Fe)3(SiO4)3(OH))
metamorphic
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Milky Quartz in Matrix
Silicon Dioxide (SiO2)
mineral
Chert (Flint)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')
Calcium Carbonate (CaCO3)
sedimentary
Banded Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Gneiss (specifically Banded Gneiss)
Gneiss
metamorphic
Gneiss
Gneiss (High-grade metamorphic rock composed primarily of Quartz, Feldspar, and various Micas)
metamorphic
Desert Rose (Gypsum Variety)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
mineral
Agate (specifically a small Chalcedony nodule)
Agate (Cryptocrystalline variety of Quartz, SiO2)
mineral
Gneiss (specifically a water-worn pebble)
Gneiss
metamorphic
Precious Opal
Hydrated Silica (SiO2·nH2O)
mineraloid
Red Jasper
Jasper (Silicon Dioxide with iron oxide inclusions), SiO2
mineral
Yellow Jasper
Silicon Dioxide (SiO2) with Goethite or Iron Oxide inclusions
sedimentary
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Sedimentary/Metamorphic Matrix
Metamorphic or Igneous (context dependent)
Hag Stone
Perforated Sandstone (composed of SiO2 and calcareous cement)
sedimentary
Septarian Nodule Segment (Turtle Stone)
Septarian Concretion (CaCO3 with Siderite or Calcite infill)
sedimentary
Turquoise
Hydrated phosphate of copper and aluminum; CuAl6(PO4)4(OH)8·4H2O
mineral