Chert (Jasper/Flint Pebble)
Microcrystalline or Cryptocrystalline Silicon Dioxide (SiO2)
sedimentary
Category
Not A Geological Specimen
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Chert (Chalcedony)
Microcrystalline quartz (SiO2)
sedimentary
Gold Nugget
Native Gold (Au)
Mineral
Banded Calcite (often sold as Mexican Onyx)
Calcium Carbonate (CaCO3)
mineral
Quartz with Mica inclusions (Gold-colored Mica)
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (Phlogopite/Muscovite) inclusions
Mineral
Basalt
Basalt (Mafic volcanic rock)
igneous
Fossiliferous Brachiopod in Shale
Brachiopoda (Phylum) preserved in Carbonaceous Shale
sedimentary
Fossiliferous Limestone
CaCO3 (principally Calcite or Aragonite)
sedimentary
Leopard Skin Jasper
Silicon Dioxide (SiO2) with impurities
sedimentary
Sandstone (Ferruginous)
Arenite (with Iron Oxide cement)
sedimentary
Quartz (likely Jasper or Chert variety)
Quartz (SiO₂)
Mineral
Quartz / Clear Quartz
Silicon Dioxide (SiO2)
mineral
Honey Calcite
Calcite (Calcium Carbonate, CaCO3)
mineral
Milky Quartz (Druzy Geode fragment)
Silicon Dioxide (SiO2)
mineral
Basalt with Quartz/Feldspar Vein
Amygdaloidal Basalt with Plutonic intrusion (SiO2/KAlSi3O8)
igneous
Fluorite (likely Green Fluorite variant)
Calcium Fluoride (CaF2)
mineral
Ferruginous Breccia
Breccia with Iron-rich (Hematite/Goethite) Matrix
sedimentary
Satin Spar (often marketed as Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
mineral
Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Chrysocolla in Matrix
Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Silicate/Secondary Copper Mineral)
mineral
Limonite Geode (Ironstone Concretion)
FeO(OH)·nH2O (Hydrated Iron Oxide)
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Pyrite
Iron Sulfide (FeS2)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Green Agate
Cryptocrystalline Quartz (SiO2)
mineral
Jasper
Jasper (Silica-rich Microcrystalline Quartz, SiO2)
sedimentary
Sandstone (Micaceous/Feldspathic variant)
Arenite (specifically subarkose or lithic arenite)
sedimentary
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Satin Spar (Gypsum)
Hydrous Calcium Sulfate (CaSO4·2H2O)
mineral
Pink Granite
Granite (Felsic Plutonic Rock)
igneous
Sandstone (specifically Arkose or Ferruginous Sandstone)
Sandstone (SiO2 predominant)
sedimentary
Granite
Phaneritic Felsic Igneous Rock (Granite)
igneous
Red Feldspar (Orthoclase)
Orthoclase Feldspar (KAlSi3O8)
mineral
Chalcedony (Agate/Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Magnetite / Iron-Rich Concretion
Magnetite (Fe3O4) or Bog Iron Limonite
mineral
Jasper (Yellow/Brown variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Milky Quartz with Iron Staining
Silicon Dioxide (SiO2)
mineral
Moss Agate
Silicon Dioxide (SiO2) with Manganese or Iron Oxide inclusions
mineral
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
sedimentary
Quartzite pebble
Quartzite (primarily SiO2)
metamorphic