Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
Category
Browse mineraloid (organic) specimens identified by the Rock Identifier community.
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
Black Pearl (Tahitian-style Cultured Pearl)
Calcium Carbonate (Aragonite) with Conchiolin (CaCO3)
Green Moss Agate / Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz with Iron and Manganese inclusions
Chert (Arrowhead Preform)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Amber
Succinite (specifically for Baltic amber); chemical formula approx. C10H16O
Shale
Shale (comprised mostly of clay minerals and quartz)
Moss Agate
Chalcedony (Silicon Dioxide / SiO2)
Shale
Fissile Mudstone (Shale)
Precious Red Coral
Corallium rubrum / Corallium japonicum
Moss Agate
Silicon Dioxide with inclusions (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert / Flint
Silicon Dioxide (SiO2)
Chert (with Limestone matrix)
Silicon dioxide (SiO2)
Chert (Jasper variation)
Chert (Microcrystalline Silicon Dioxide, SiO2)
Red Jasper
Jasper (Silicon Dioxide, SiO2)
Glauconitic Sandstone (Greensand)
Glauconitic Sandstone (Iron-potassium phyllosilicate mineral: (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
Chert (often called Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (often called Flint in various colors)
Silicon Dioxide (SiO2)
Chert (and Chalcedony)
Silicon Dioxide (SiO2)
Chert (Beach Pebble)
Microcrystalline Quartz (SiO2)
Chert (Flint)
Chert (SiO2)
Pearl
Calcium Carbonate (primarily Aragonite and Calcite), CaCO3
Graphite
Graphite (Carbon, C)
Micro-crystalline Quartz Pebble (Chert)
Silicon dioxide (SiO2)
Chert (including Flint and Jasper variants)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Graphite
Graphite (Native Carbon), Formula: C
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
Chert (Black Chert / Flint)
Silicon Dioxide (SiO2)
Fossil Coral
Cnidaria Anthozoa (Fossilized)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Chert (often called Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Jasper)
Silicon dioxide (SiO2)
Petrified Wood
Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)
Chert (Black Chert/Flint)
Silicon Dioxide (SiO2)
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with inclusions
Ironstone Concretion (Limonite/Goethite)
Iron oxide concretion (contains FeO(OH)·nH2O)
Moss Agate
Chalcedony (SiO2) with inclusions of manganese or iron oxides
Petrified Wood
Silicified Wood (SiO2)
Moss Agate
Silicon Dioxide (SiO2) with Chlorite/Oxide inclusions
Lemon (Mock specimen mimicking Citrine/Sulfur)
Citrus x limon
Fossiliferous Limestone with Rugose Coral
Calcite (CaCO3) matrix containing Rugosa (order of extinct solitary and colonial corals)
Petrified Wood
Silicified Wood (SiO2 - Silicon Dioxide)