Porphyritic Basalt
Porphyritic Basalt with Olivine phenocrysts
igneous
Category
Not A Geological Specimen
Browse not a geological specimen specimens identified by the Rock Identifier community.
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Riverstone (Sandstone Pebble)
Arenite (SiO2 with various lithic fragments)
sedimentary
Fossilized Brain Coral
Diploria labyrinthiformis (Fossilized)
sedimentary
Calamites Fossil (Horsetail Stem)
Calamites (Genus), part of the class Equisetopsida
sedimentary
Limonite (Ironstone Concretion)
Hydrous ferric oxides (FeO(OH)·nH2O)
mineral
Fossil Coral
Cnidaria Anthozoa (Fossilized)
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula: SiO2)
sedimentary
Concrete / Anthropogenic Conglomerate
Man-made composite material (Portland cement, aggregate, and water)
not a natural rock
Chert with Asphaltum (or Tar)
Silica (SiO2) with natural Bitumen/Asphaltum
sedimentary
Concretion
Septarian Concretion
sedimentary
Limonite (Ironstone Concretion)
Limonite: FeO(OH)·nH2O
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Fossilized Coral (Petrified Coral)
Anthozoa (Scleractinia)
sedimentary
Dog (Sleeping)
Canis familiaris (or Canis lupus familiaris)
Organic/Biological
Basalt Column Section
Columnar Basalt (Mafic Extrusive Igneous Rock)
igneous
Septarian Nodule (Septarian Stone)
Septarian Concretion (CaCO3 with Siderite/Calcite/Aragonite)
sedimentary
Fossilized Favosites (Honeycomb Coral)
Favosites (extinct genus of tabulate coral)
sedimentary
Fossilized Coral
Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)
sedimentary
Petrified Wood / Red Jasper
Silicified wood (primarily Silicon Dioxide, SiO2)
sedimentary
Fossilized Gastropod in Limestone
Gastropoda (Class) in Fossiliferous Limestone
sedimentary
Peanut Wood
Silicified (Petrified) Wood - SiO2 (Silicon Dioxide)
sedimentary
Metal Alloy (Likely Pewter or Sterling Silver)
Not a natural geological specimen; composed of refined metals. If pewter, it's a tin-based alloy. If sterling silver, it's 92.5% silver and 7.5% other metals (usually copper).
Man-made material (metal)
Amethyst
Quartz (Silicon Dioxide) SiO2 + Fe4
mineral
Fossilized Coral
Cnidaria (Anthozoa), often replaced by Calcium Carbonate (CaCO3) or Silica (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Septarian Nodule (Micro-fragment)
Septarian Nodule / Concretion (CaCO3 + CaMg(CO3)2 + Quartz)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Fossil Coral (Petoskey Stone / Rugose Coral)
Hexagonaria percarinata (Order: Rugosa, Fossilized Calcium Carbonate CaCO3)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, SiO2)
mineral
Agatized Fossil (Druzy Agate)
Silicon Dioxide (SiO2) replacing organic matter
sedimentary
Septarian Nodule
Septarian Concretion (Calcium Carbonate/Aragonite/Calcite)
sedimentary
Petrified Wood
Silicified wood (principally Silicon Dioxide, SiO2)
sedimentary
Moqui Marble (Iron Concretion)
Hematite/Goethite Concretion (Fe2O3 / FeO(OH))
sedimentary
Petrified Wood
Silicified wood (Quartz variant, SiO2)
sedimentary
Gold Ore (in Quartz/Sulfide matrix)
Native Gold (Au) in Quartz (SiO2) and Pyrite (FeS2)
mineral
Quartzite Pebble
Metamorphosed Sandstone (SiO2)
metamorphic
Vesicular Basalt with Epidote/Amygdaloidal Basalt
Amygdaloidal Basalt (Mg, Fe)2SiO4 + Ca2(Al, Fe)3(SiO4)3(OH)
igneous
Limonite (Ironstone) Concretion
FeO(OH)·nH2O (Hydrous ferric oxide)
sedimentary
Sandstone (with differential weathering)
Arenite / Quartz Sandstone (SiO2)
sedimentary
Pyrite in Shale
Iron Sulfide (FeS2) in Argillaceous Shale
sedimentary
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral