Chert
Microcrystalline silica (SiO2)
Category
Browse organic structure (not a rock) specimens identified by the Rock Identifier community.
Chert
Microcrystalline silica (SiO2)
Chert (Chalcedony/Agate Pebble)
Cryptocrystalline Silica (SiO2)
Amber
Succinite
Baltic Amber
Succinite (Fossilized Tree Resin)
Coal
Anthracite or Bituminous Coal
Cardstock (Paper)
Cellulose (C6H10O5)n
Human Skin (Epidermis/Dermis)
Integumentary tissue (High content of hydroxyapatite in bones, though the surface is biological)
Petrified Wood
Silicified Wood (primarily SiO2 - Silicon Dioxide)
Shungite
Shungite (Non-crystalline carbon, C)
Pearl
Calcium Carbonate (CaCO3) with Conchiolin
Petrified Wood
Silicified Wood (primarily SiO2)
Chert / Flint
Chert (Microcrystalline Quartz, SiO2)
Petrified Wood
Petrified Wood (Silicified Wood)
Chert (Flint Nodules)
Microcrystalline Quartz (SiO2)
Chert (Nodule)
Microcrystalline Quartz (SiO2)
Freshwater Pearl
Aragonite / Biogenic Calcium Carbonate (CaCO3)
Weathered porphyritic basalt
Basalt, likely plagioclase-phyric basalt; primarily a fine-grained aggregate of plagioclase feldspar, clinopyroxene, and possibly olivine or iron-titanium oxides
Jasper
Silicon Dioxide (SiO2) microcrystalline quartz
Chalcedony (Common Agate)
Silicon Dioxide (SiO2)
Petrified Wood
Silicified Wood (primarily quartz/chalcedony replacing organic wood structure)
Limestone
Calcium Carbonate (CaCO3)
Fossiliferous Limestone
Bioclastic Limestone (CaCO3)
Pyrite
Iron Sulfide (FeS2)
Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite
Calcareous Tufa (or Travertine)
Calcium Carbonate (CaCO3)
Fossilized Tooth Fragment
Vertebrate Fossil (Mammalia indet.)
Pyrite
Iron Sulfide (FeS2)
Chert Nodules in Limestone
Cryptocrystalline Quartz (SiO2) within Calcium Carbonate (CaCO3)
Jasper
Microcrystalline Quartz (SiO2)
Chert (Flint)
Microcrystalline Silica (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert (specifically Red Chert or Jasper)
Microcrystalline Quartz (SiO2)
Chert (Jasper/Mudstone)
Microcrystalline Quartz (SiO2)
Chert (potentially Jasper)
Microcrystalline Quartz (SiO2)
Fossil Shark Tooth (Otodus obliquus)
Otodus obliquus; hydroxyapatite (mineralized form Ca5(PO4)3(OH))
Glauconitic Sandstone (or Greensand)
Glauconitic Siliciclastic Rock (Containing (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)
Jasper
Microcrystalline Quartz (SiO2)
Chert (specifically Brown Chert or Jasper)
Microcrystalline Quartz (SiO2)
Jasper
Microcrystalline Quartz (SiO2)
Freshwater Pearl
Calcium Carbonate (CaCO3) - Aragonite/Calcite organic composite
Chert (Jasper)
Microcrystalline Quartz (SiO2)