Agate
Agate (a cryptocrystalline variety of Quartz, SiO₂)
Category
Browse anthropogenic specimen (man made material) specimens identified by the Rock Identifier community.
Agate
Agate (a cryptocrystalline variety of Quartz, SiO₂)
Quartz (in matrix)
Quartz (SiO₂)
Chalcedony or Chert/Jasper with secondary mineral staining
SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.
Pink Stained Rock (Likely Quartzite or Sandstone with Iron Oxide Staining)
Quartzite (metamorphic) or Sandstone (sedimentary); coloration likely due to hematite or other iron oxides.
Flint / Chert
Silicon dioxide (SiO2)
Quartz Geode/Druzy Quartz
Quartz (SiO₂)
United States Quarter Dollar
Cupronickel Clad Alloy (75% Copper, 25% Nickel over a 100% Copper core)
Iron Meteorite
Siderite (Iron-Nickel Meteorite)
Milky Quartz
Silicon Dioxide (SiO2)
Amethyst
SiO2 (Silicon Dioxide)
Banded Chert
Silicon Dioxide (SiO2)
Quartz
SiO₂ (Silicon Dioxide)
Turquoise
Turquoise (CuAl6(PO4)4(OH)8·4H2O)
Petrified Wood
Silicified Wood (primarily SiO2)
Coal (most likely Bituminous or Anthracite)
Bituminous Coal (Grade of Coal), Anthracite (Grade of Coal)
Quartz (likely Jasper or Chert variety)
Quartz (SiO₂)
Agate (Nodule/Chert)
Silicon Dioxide (SiO2)
Sandstone (Tumbled/River Pebble)
Arenite (composed primarily of SiO2)
White Marble
Recrystallized Calcite (CaCO3)
Chert (Jasper)
Silicon dioxide (SiO2)
Laterite (iron-rich nodule, possibly Bauxite as a subtype)
Laterite (composed of various minerals including goethite, hematite, gibbsite, etc.)
Turquoise
Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]
Limestone
Calcite (CaCO3)
Quartz (likely a weathered/tumbled piece)
Quartz (SiO₂)
Slate
Slate (Foliated metamorphic rock)
Milky Quartz
Silicon Dioxide (SiO2)
Quartz (likely a macrocrystalline variety like milky quartz or smoky quartz, given the appearance in the image)
Quartz (SiO₂ - Silicon Dioxide)
Scoria
Vesicular Basaltic Glass
Limestone
Calcium Carbonate (CaCO3)
Limonite (Iron Ore)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
Quartz
Quartz (SiO2, Silicon Dioxide)
Diorite (Polished Tumble)
Diorite (Intermediate intrusive igneous rock)
Chert (often called Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz Geode (likely within Limestone or Dolomite matrix)
Quartz (SiO₂)
Coquina / Limonite-stained Limestone
Sedimentary Limestone with Iron Oxyhydroxide (FeO(OH)·nH2O)
Quartz (possibly milky quartz or quartz with inclusions)
SiO2 (Silicon Dioxide)
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
Septarian Nodule (Galt)
Calcareous concretion / Septarian concretion
Thunderegg (specifically a Jasper/Agate-filled Geode nodule)
Silicon Dioxide (SiO2) within Rhyolitic Matrix
Fossiliferous Limestone
Fossiliferous Calclutite / Bio-calcarenite (CaCO3)
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
Chert
Microcrystalline Quartz (SiO2)