Glauconitic Sandstone
Glauconitic sandstone ((K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)
Category
Browse mineraloid (organic) specimens identified by the Rock Identifier community.
Glauconitic Sandstone
Glauconitic sandstone ((K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)
Precious Red Coral
Corallium rubrum (Calcium Carbonate, CaCO3)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Fossilized Shark Tooth
Carcharocles or Otodus sp. (Micro-fossilized)
Pyrite (Fool's Gold) Cube
Iron Sulfide (FeS2)
Chert (Jasper)
Cryptocrystalline Silicon Dioxide (SiO2)
Chert (Nodule)
Chert (Silicon Dioxide, SiO2)
Limestone (Fossiliferous)
Calcium Carbonate (CaCO3) - Bioclastic Limestone
Flint (Chert)
Silicon Dioxide (SiO2)
Chalcedony (Common Opal variant)
Silicon dioxide (SiO2) with varying levels of hydration
Banded Chert / Jasper
Silicon Dioxide (SiO2)
Fossil-bearing Sedimentary Rock
Sedimentum cum fossili
Amber
Succinite (fossilized tree resin)
Coal (Anthracite or Bituminous)
Carbonaceous sedimentary rock (Carbon)
Pearl
Nacre (aragonite, CaCO₃, with conchiolin)
Pearl
Nacre (aragonite, CaCO₃, in a conchiolin matrix)
Amber
Succinite (approximate formula C10H16O)
Petrified Wood
Silicified Wood (SiO2)
Pyritized Ammonite
Ammonitida (replaced by Iron Disulfide, FeS2)
Amber
Succinite
Pearl
Calcium carbonate (principally Aragonite, CaCO3) with Conchiolin
Fossilized Nut / Coprolite / Concretion
Trace Fossil / Permineralized Plant Material
Coal
Anthracite / Bituminous Coal
Fossiliferous Limestone
Calcite-rich Fossiliferous Limestone (CaCO3)
Likely bituminous coal
Coal, predominantly carbon-rich organic matter; exact rank cannot be confirmed visually
Petrified wood
Silicified wood, commonly quartz (SiO₂) replacing woody tissue
Chert (likely brown flint)
Microcrystalline quartz, SiO₂ (chalcedonic quartz aggregate)
Plume Agate
Cryptocrystalline Quartz (SiO2)
Amber
Succinited (C10H16O)
Travertine
Calcareous tufa (CaCO3)
Stardust (Micrometeorite)
Chondrite / Micrometeorite (Extraterrestrial Silicate)
Moss Agate
Chalcedony (SiO2) with inclusions of hornblende or chlorite
Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxides
Limestone
Calcium Carbonate (CaCO3)
Agatized Fossil (Druzy Agate)
Silicon Dioxide (SiO2) replacing organic matter
Fossiliferous Limestone with Fossil Fragment
Fossiliferous Limestone (CaCO3 with organic remains)
Red Coral (Precious Coral)
Corallium rubrum (Calcium Carbonate, CaCO3)
Amber
Succinite (organic gemstone, approx. C10H16O)
Coal
Bituminous Coal (organic sedimentary rock)
Weathered River Rock (likely Chert or Basalt with algae)
Silicon dioxide (SiO2) with organic biofilm
Mother of Pearl (Nacre)
Aragonite (layered with organic polymers), CaCO3
Limestone with Bitumen/Chert
Calcite (CaCO3) containing organic hydrocarbons