Sandstone Concretion
Sedimentary Concretion (Quartz sand bound by mineral cement)
sedimentary
Category
Organic Materia (Not A Rock Or Mineral)
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Fossil Shell (Bivalve)
Class Bivalvia (fossilized)
fossil
Granite
Intrusive Igneous Rock
igneous
Sandstone
Arenite (SiO2 based typically)
sedimentary
Travertine (Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Garnet-bearing Schist / Conglomerate Specimen
Metamorphic rock with almandine garnet porphyroblasts
metamorphic
Petrified Wood
Silicified Wood (primarily quartz/chalcedony replacing organic wood structure)
fossil
Geode half
Geode (often quartz/chalcedony based)
sedimentary or igneous
Amygdaloidal Basalt with Zeolite/Quartz Infill
Amygdaloidal Basalt (Host: (Mg,Fe)2SiO4 / CaAl2Si2O8; Infill: SiO2 or Na2Al2Si3O10·2H2O)
igneous
Concrete
Anthropogenic Conglomerate
sedimentary
Granite
Intrusive Igneous Rock
igneous
Quartz Geode
Silicon Dioxide (SiO2) within a secondary sedimentary structure
sedimentary
Chert (River Pebble)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (variations include Flint/Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Epidote
Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))
mineral
Basalt with Quartz Veins
Mafic Igneous Rock (primarily Plagioclase and Pyroxene) with SiO2 inclusions
igneous
Amber
Succinates (Organic compound: C10H16O)
mineraloid
Red Siltstone (or Red Shale)
Clastic Sedimentary Rock (Composition: primarily Quartz, Clay minerals, and Hematite Fe2O3)
sedimentary
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) in matrix
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Limonite (after Pyrite Pseudomorph)
Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)
mineral
Serpentine
(Mg,Fe)3Si2O5(OH)4
metamorphic
Granite
Felsic intrusive igneous rock
igneous
Granite
Felsic intrusive igneous rock
igneous
Sandstone (Common Quartz Pebble/Rock)
Sedimentary rock / Quartz arenite
sedimentary
Chert (specifically Banded Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (with Lichen)
Microcrystalline Quartz (SiO2)
sedimentary
Porphyry
Porphyritic Igneous Rock
igneous
Amphibolite
Amphibolite
metamorphic
Boulder Opal
Hydrated Silica (SiO2·nH2O)
mineraloid
Basalt with Weathering Rind
Basalt (Mafic Volcanic Rock)
igneous
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Volcanic Rock)
Igneous
Granite
Granite
Igneous
Granite
Felsic intrusive igneous rock
igneous
Granite
Felsic intrusive igneous rock
igneous
Chalcedony / Agate Pebble
Silicon Dioxide (SiO2)
mineral
Speckled rounded stone, likely granite or granitic gneiss
Granite/granitic gneiss; primarily quartz (SiO₂), feldspar, and dark mica or amphibole
igneous
Quartz (Milky Quartz vein fragment)
Silicon Dioxide (SiO2)
mineral
Amygdaloidal Basalt
Extrusive Igneous Rock with Amygdules
igneous
Brown Chalcedony
Silicon Dioxide (SiO2)
mineral
Bauxite
Bauxite (Al2O3·2H2O mixed with iron oxides)
sedimentary
Quartz
Silicon Dioxide (SiO2)
mineral