Vesicular Basalt (Scoria)
Basalt (Extrusive Igneous Rock)
igneous
Category
Not A Geological Specimen
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Rock Crystal Quartz
Quartz (SiO₂)
Mineral
Limonite (often after Pyrite)
Limonite (FeO(OH)·nH2O)
mineral
Rose Quartz
Silicon Dioxide (SiO2) with trace elements of Titanium, Iron, or Manganese
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Orange Quartz with Hematite inclusions
Quartz (SiO2) with Hematite (Fe2O3) inclusions
Mineral
Yellow Chalcedony
Chalcedony (a cryptocrystalline variety of Quartz, SiO₂)
Mineral
Jasper (Iron-stained Chert)
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Staurolite (Fairy Cross)
Staurolite (Fe2+2Al9Si4O23(OH))
metamorphic
Pyrite
Iron Disulfide (FeS2)
mineral
Quartz
Silicon dioxide (SiO₂)
Mineral
River Rock (likely Basalt or Greywacke)
Basalt or Lithic Sandstone
Igneous or Sedimentary (water-worn)
Quartz (pebble)
Quartz (SiO₂)
Mineral
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Granite Pebble
Granite (Felsic Intrusive Igneous Rock)
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Chert (Iron-stained River Cobble)
Microcrystalline Quartz (SiO2)
sedimentary
Granite Cobble
Phaneritic Felsic Igneous Rock
igneous
Amygdaloidal Basalt
Basalt with secondary mineral infilling
igneous
Black Obsidian
Volcanic Glass (predominantly SiO2)
igneous
Quartz Vein in Host Rock
Crystalline Silicon Dioxide (SiO2) in Pelitic or Shaly Matrix
metamorphic
Gold Nugget
Native Gold (Au)
mineral
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Mineral
Gneiss
Gneiss
metamorphic
Granite Pebble
Granite (a phaneritic intrusive igneous rock consisting of quartz, alkali feldspar, and plagioclase)
igneous
Basalt (Water-worn Pavement Stone)
Basalt (Mafic Extrusive Igneous Rock)
igneous
Rhodochrosite
Manganese Carbonate (MnCO3)
mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3/FeO(OH)) inclusions
mineral
Banded Agate (specifically Botryoidal/Orbicular Agate)
Silicon Dioxide (SiO2)
Mineral (variety of Chalcedony/Quartz)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Trilobite Fossil in Limestone
Trilobita (Class), likely embedded in fossiliferous limestone (CaCO3)
fossil
Opalite
Synthetic Opalite (Man-made glass)
mineral
River Stone / Pebble
Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)
Mineral, Sediment
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Quartz
Quartz (SiO2 - Silicon Dioxide)
Mineral
Rough Corundum (likely Sapphire or Common Corundum)
Aluminum oxide (Al2O3)
mineral
Aquamarine on Feldspar Matrix
Beryl (Be3Al2Si6O18) with Potassium Feldspar (KAlSi3O8)
mineral
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Concrete Paver (Artificial Cementitious Rock)
Hydrated Portland Cement Aggregate
Sedimentary (Synthetic)
Biotite Schist
Biotite Schist (K(Mg,Fe)3AlSi3O10(OH,F)2)
metamorphic
Limonite and Goethite (Ironstone)
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Banded Rock (likely Quartz-rich)
Uncertain, likely a Metamorphic Rock (e.g., Gneiss or Schist) with prominent Quartz and other minerals
Mineral