Sandstone (likely Arkose)
Arenite (Feldspathic Sandstone / Arkose)
Category
Browse mineral description (anthropogenic material) specimens identified by the Rock Identifier community.
Sandstone (likely Arkose)
Arenite (Feldspathic Sandstone / Arkose)
Sandstone (Quartzose Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 staining)
Milky quartz
Quartz (silicon dioxide, SiO₂)
Moss Agate
Silicon Dioxide (SiO2) with inclusions
Chert / Jasper
Silicon Dioxide (SiO2)
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
Petrified Wood
Silicified Wood (SiO2)
Granite
Phaneritic Felsic Igneous Rock (Granite)
Granodiorite
Granodiorite (Na,Ca)(Al,Si)4O8
Rhyolitic Tuff
Rhyolitic Tuff / Pyroclastic rock
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Agate (specifically, multi-colored or pastel-dyed agate)
Silicon dioxide (SiO2) - specifically, a cryptocrystalline variety of quartz known as Chalcedony, with banding classified as Agate. (If it were Fluorite, the chemical formula would be Calcium Fluoride - CaF2).
Chert (Nodule)
Microcrystalline Quartz (SiO2)
Chert / Chalcedony
Silicon Dioxide (SiO2)
Sandstone (Red Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide)
Rhodonite
Rhodonite ((Mn2+,Fe2+,Mg,Ca)SiO3)
K2 Jasper
Azurite in Granite
Tumbled blue quartzite or blue chalcedony (uncertain)
Quartz-rich rock; predominantly silicon dioxide (SiO₂)
Sandstone (with vugs or solution cavities)
Arenite (primarily Quartz and Feldspar with CaCO3 or SiO2 cement)
Fossilized Shark Tooth (Eroded)
Carcharodon sp. or Otodus sp. fragment (likely)
Sand Tiger Shark Tooth (Fossil)
Carcharias taurus (fossilized dentin/enameloid)
Limestone with Calcite
Sedimentary Calcium Carbonate (CaCO3)
Petrified Wood
Silicified Wood (SiO2)
Jasper
Silicon dioxide (SiO2)
Schist (Greenschist / Mica Schist)
Metamorphic rock rich in platy minerals (e.g., Chlorite/Mica schist)
Sandstone
Arenite (SiO2 based with various mineral cements)
Sandstone
Arenite (Siliclastic sedimentary rock)
Granite
Granite
Likely polished dark stone or glassy mineral bead
Indeterminate; possibly obsidian, hematite, or a dark agate
Milky quartz with iron-oxide staining
Quartz (silicon dioxide, SiO₂), commonly intergrown massive quartz
Weathered river stones, likely basaltic andesite and related volcanic rocks
Fine-grained mafic/intermediate volcanic rocks; commonly basalt (plagioclase + pyroxene ± olivine) or andesite (plagioclase + pyroxene ± amphibole)
Sandstone (Ferruginous)
Arenite (with iron oxide cement)
Granite
Granite (Felsic Plutonic Rock)
Tektite
Impactite (Natural Silicate Glass)
Quartz pebble (Quartzite / Chert)
Silicon Dioxide (SiO2)
Rough Diamond
Diamond (Native Carbon, C)
Aura Quartz
Titanium-coated Silicon Dioxide (SiO2)
Citrine Quartz
Crystalline Quartz (SiO2) with iron impurities
Chrysocolla Chalcedony
Hydrated Copper Phyllosilicate (Cu,Al)2H2Si2O5(OH)4 + SiO2
Grey Chalcedony (Tumbled)
Chalcedony (SiO2)
Diamond
Native Carbon (C)
Conglomerate
Clastic Sedimentary Conglomerate (SiO2, CaCO3 dominant)