Amethyst Geode
Quartz (Silicon Dioxide, SiO2) with iron impurities
mineral
Category
Sedimentary Rock (Specifically A Concretion Or Possibly A Geode)
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Quartz (likely Herkimer Diamond style)
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Basalt
Basalt (composition predominately plagioclase feldspar and pyroxene)
igneous
Likely weathered quartz-rich stone
Indeterminate; possibly quartz-bearing granite or milky quartz
mineral
Agate / Chalcedony Geode
Silicon Dioxide (SiO2)
sedimentary
Basalt with Vesicle/Vug
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Chalcedony (Agate/Quartz)
Silicon Dioxide (SiO2)
mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Septarian Nodule (Septarian Dragon Stone)
Septarian Concretion (Composition: Calcite, Aragonite, and Limestone/Clay)
sedimentary
Leopard Skin Jasper
Orbicular Jasper (Silicon Dioxide, SiO2)
sedimentary
Agate Geode Slice (with Druzy Quartz)
Silicon Dioxide (SiO2)
mineral
Geode Nodules / Chalcedony Geode
Silicon Dioxide (SiO2) - Amorphous to Cryptocrystalline Quartz
sedimentary
Vesicular Basalt (Scoria)
Extrusive Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
igneous
Quartz (Druzy or Geode fragment)
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Sandstone
Clastic Sedimentary Rock (composed mostly of quartz, SiO2)
sedimentary
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Septarian Nodule
Septarian concretion (Calcite, Aragonite, and Limestone)
sedimentary
Banded Agate with Drusy Quartz
Cryptocrystalline Quartz (SiO2) with macrocrystalline Quartz
mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Dalmation Jasper (or Dalmation Stone)
Dalmation Stone (composed of Perthite, Quartz, and Arfvedsonite)
igneous
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Mixed river stones and gravel
Polymictic alluvial clasts; individual pieces may include quartzite, granite, basalt, sandstone, limestone, and slate
igneous, sedimentary, metamorphic
Chert (Agatized/Chalcedony variety)
Microcrystalline Quartz (SiO2)
sedimentary
Dragon Vein Agate
Silicon Dioxide (SiO2)
mineral
Quartz Geode Segment
Crystalline Silicon Dioxide (SiO2)
mineral
Quartz-lined Geode / Chalcedony Nodule
Silicon Dioxide (SiO2)
sedimentary
Agate Geode with Quartz Druzy
Chalcedony (SiO2) and Quartz (SiO2)
mineral
Chert Nodules or Concretion
Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint) with Limestone Matrix
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
sedimentary
Limonite/Goethite Iron Concretion
Hydrated iron oxide-hydroxide mixture (FeO(OH)·nH2O)
mineral
Limestone with Fossil Inclusion
Calcium Carbonate (CaCO3)
sedimentary
Quartz with Calcite
Silicon Dioxide (SiO2) / Calcium Carbonate (CaCO3)
mineral
Dark river pebble (likely basalt or andesite)
Fine-grained mafic/intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene/olivine)
igneous
Ironstone Concretion (Limonite/Goethite)
Goethite-rich Concretion (FeO(OH))
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Sandstone (likely Graywacke or Lithic Arenite)
Clastic sedimentary rock predominantly composed of silicate grains
sedimentary
Chert / Flint Nodules in Sandstone
Microcrystalline Quartz (SiO2) within Clastic Sedimentary Rock
sedimentary