Chert (Chalky/Gray Variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Category
Browse organic mineraloid specimens identified by the Rock Identifier community.
Chert (Chalky/Gray Variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Chert Nodule)
Microcrystalline quartz (SiO2)
Chert (Nodule)
Microcrystalline Quartz (SiO2)
Chert (and/or River Pebble)
Microcrystalline silica (SiO2)
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
Pyrite in Shaly Matrix
Iron Sulfide (FeS2)
Chert (and Jasper variety)
Microcrystalline Quartz (SiO2)
Peacock Ore
Bornite (Cu5FeS4) or Chalcopyrite (CuFeS2) with iridescent tarnish
Tumbled amber-like inclusion
Likely amber (fossilized tree resin; complex polymer), but identification is uncertain from the image
Petrified Wood
Silicified Wood (SiO2 - Quartz/Chalcedony replacement)
Petrified Wood
Silicified Wood (SiO2)
Chert (specifically a nodule with Chalcendony/Agate banding)
Microcrystalline Quartz (SiO2)
Limestone
Calcium carbonate (CaCO3)
Petrified wood
Silicified wood, chiefly microcrystalline quartz (SiO₂)
Petrified Wood
Silicified Wood (SiO2)
Dendritic Agate / Moss Agate
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
Green Moss Agate
Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite
Precious Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
Moss Agate
Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite
Petrified Wood
Silicified Wood (primarily SiO2)
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with dendritic inclusions
Shale
Clastic sedimentary rock (primarily clay and silt minerals)
Opalite
Synthetic Opalised Glass
Likely chert or flint
Microcrystalline quartz (SiO₂), commonly called chert; exact identification requires testing
Amber (or polished Chalcedony bead)
Fossilized Tree Resin / SiO2 (Silicon Dioxide if Chalcedony)
Honey Calcite
Calcium Carbonate (CaCO3)
Orange Calcite
Calcium Carbonate (CaCO3)
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide
Agate (Yellow Moss Agate)
Cryptocrystalline Quartz (SiO2)
Ironstone Concretion (Ironstone Gourd)
Limonite/Goethite Concretion (FeOO(H))
Calcareous Tufa / Limestone Fragment
Calcium Carbonate (CaCO3)
Pink Opal
Hydrated silicon dioxide (SiO2·nH2O) with inclusions
Chert (Nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Moss Agate
Silicon Dioxide with inclusions (SiO2 + impurities)
Shale or Siltstone
Sedimentary Clastic Rock (Variable mineral composition including quartz and clay minerals)
Fossilized Sand Tiger Shark Tooth
Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)
Moss Agate
Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide
Chert (Brecciated Chert)
Silicon Dioxide (SiO2)
Petrified Wood (Black / Carbonized)
Silicon Dioxide (Quartz/Chalcedony replacing Organic Matter)
Favosites Fossil (Honeycomb Coral)
Favosites (Extinct genus of Tabulate Coral)
Petrified Wood
Silicified Wood (primarily SiO2)