Sandstone Concretion
Clastic Sedimentary Concretion (typically Quartz/Silica with Iron Oxide)
sedimentary
Category
Metamorphic Or Sedimentary Depending On Local Grade
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Clear Quartz
Silicon Dioxide (SiO2)
mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Yellow Calcite
Calcium Carbonate (CaCO3)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Magnetic Sand Grain / Magnetite Pellet
Magnetite (Fe3O4)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Quartz Crystal Fragment
Silicon Dioxide (SiO2)
mineral
Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Note: Image shows a biological specimen (Rat), not a rock. Representative geological equivalent: Galena (due to lead-grey colors in fur).
Galena (PbS)
mineral
Quartz (Granular)
Silicon Dioxide (SiO2)
mineral
Serpentine
Serpentinite (rock) containing serpentine minerals (e.g., Antigorite, Lizardite, Chrysotile)
Metamorphic rock
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Chert (varietal: Jasper or Flint)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Sandstone with Iron Staining
Arenite with Limonite/Hematite inclusions (SiO2 + Fe2O3/FeO(OH))
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Green Jasper
Jasper (variety of Microcrystalline Quartz, SiO2)
sedimentary
Red Ochre (Hematite-rich Clay)
Limonitic/Hematitic Claystone (Fe2O3 with clay minerals)
Sedimentary
Banded Chert (Flint)
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Jasper/Flint var.)
Silicon Dioxide (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
mineral
Green Jasper (Agate-Jasper mixture)
Silicon Dioxide (SiO2) with impurities
sedimentary
Citrine Quartz
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
White Opal
Hydrated Silica (SiO2·nH2O)
mineral
Ironstone with Limonite/Goethite coating
Ferruginous Sedimentary Rock (contains Limonite FeO(OH)·nH2O)
sedimentary
Shale or Slate with Quartz Veins
Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins
Metamorphic, likely Sedimentary with Quartz veins
Emerald (Rough)
Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)
mineral
Sandstone with Quartz Veining
Arenite with hydrothermal quartz (SiO2)
sedimentary
Blue Tiger's Eye
Crocidolite (fibrous riebeckite) silicified to Quartz (SiO2)
Mineral
Banded Iron Formation (BIF)
Banded Iron Formation (predominantly Hematite, Magnetite, and Chert/Quartz)
sedimentary
Amethyst Geode
Amethyst (SiO2) - Silicon Dioxide with Trace Iron Impurities
mineral
Chalcedony (Common Opal variant)
Silicon dioxide (SiO2) with varying levels of hydration
mineral
Chalcedony (Moonstone-like Agate)
Silicon Dioxide (SiO₂)
mineral
Nephrite Jade
Nephrite (Ca2(Mg, Fe)5Si8O22(OH)2)
metamorphic
Lapis Lazuli
Lapis Lazuli (Complex aggregate of Lazurite, Calcite, and Pyrite)
metamorphic
Lapis Lazuli
Lazurite-dominated contact metamorphic rock
metamorphic
Conglomerate
Conglomerate (Sedimentary Clastic Rock)
sedimentary
Chalcedony (Yellow/Amber variety)
Silicon Dioxide (SiO2)
mineral
Garnet (Almandine or Spessartine likely)
Garnet Group Minerals (e.g., Almandine Fe3Al2(SiO4)3, Pyrope Mg3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3)
Mineral
Topaz
Topaz (Al2SiO4(F,OH)2)
Mineral