Unidentifiable Rock Fragment
Category
Sedimentary Rock (Specifically A Clastic Sedimentary Rock Formed Into A Cobble)
Browse sedimentary rock (specifically a clastic sedimentary rock formed into a cobble) specimens identified by the Rock Identifier community.
Crinoid Fossil in Limestone
Crinoid (Class Crinoidea) in Fossiliferous Limestone (CaCO3)
Quartz / River Cobble
Silicon Dioxide (SiO2)
Opal
Hydrated Silica (SiO2·nH2O)
Basalt with Quartz Veining
Basalt (Mafic Volcanic Rock with SiO2)
Concretion
Septarian concretion (likely containing Calcite or Siderite)
Limestone
Limestone (Calcium Carbonate - CaCO3)
Limestone
Calcareous sedimentary rock (CaCO3)
Jasper-Quartz Conglomerate / Chert
Siliceous Sedimentary Rock (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Siltstone
Siltstone (siliciclastic sedimentary rock)
Limestone
Calcium Carbonate (CaCO3)
Quartzite (River Cobble)
Metamorphic Quartz-rich Rock
Blue Lace Agate
Silicon dioxide (SiO2) - Chalcedony variety
Limestone
Calcium Carbonate (CaCO3)
Basalt River Stone
Basalt
Man-made Jewelry (Metal and Glass/Plastic)
Synthetic Alloy and Amorphous Solid (SiO2/Polymer)
Chert (Jasper variation)
Silicon dioxide (SiO2)
Jasper
Silicon dioxide (SiO2)
Chert (often called Flint in dark varieties)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Chert Breccia (Yellow Jasper)
Silicon Dioxide (SiO2) - Brecciated Chert
Bauxite / Iron-rich Laterite
Laterite (principally Al(OH)3, Fe2O3, and SiO2)
Geode (unopened) or Calcareous Nodule
Siliceous or Calcareous Concretion/Nodule
Chert Geode or Nodule
Microcrystalline Quartz (SiO2)
Basalt (River Cobble)
Basalt (Mafic volcanic rock)
Limestone
Calcium Carbonate (CaCO3)
Chert / Flint
Microcrystalline Quartz (SiO2)
Diorite (River Cobble)
Intermediate Phaneritic Plutonic Rock
Ferruginous Quartz
Quartz with Iron Oxide inclusions (SiO2 + Fe2O3)
Chert (Tan/Yellow variety)
Microcrystalline quartz (SiO2)
Coal (most likely Bituminous or Anthracite)
Coal (organic sedimentary rock)
River Rock
Sedimentary Rock (various compositions)
Chert (Brecciated Chert)
Silicon Dioxide (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Sand Dollar Fossil
Echinoidea (Clypeasteroida)
Pink Granite / Gneiss
Felsic Plutonic Rock (Granite) with Gneissic banding
Ruby (Pinkish-Red)
Corundum (Al2O3 with Chromium trace)
Ocean Jasper
Silicon Dioxide (SiO2) with various inclusions
Quartz Geode
Silicon Dioxide (SiO2)
Collection of Minerals and Ores
Various (e.g., Uraninite (U3O8), Carbon (C), Native Gold (Au), Hematite (Fe2O3), Galena (PbS), etc.)
Shale or Mudstone (Based on appearance)
Shale (fine-grained, laminated fissile sedimentary rock) / Mudstone (fine-grained, non-fissile sedimentary rock)