Tumbled basalt
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, pyroxene, and commonly olivine
igneous
Category
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Black basalt
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase, pyroxene, and commonly olivine
igneous
Schist
Mica Schist
metamorphic
Sandstone (Ferruginous/Banded)
Clastic Terrigenous Sandstone (SiO2 with Fe2O3 cement)
sedimentary
Garnet Schist
Almandine Garnet in Mica Schist
metamorphic
Serpentinite
Serpentinite (group of hydrous magnesium iron phyllosilicates)
metamorphic
Granite
Phaneritic plutonic rock (SiO2 + Al2O3)
igneous
Serpentinite
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
metamorphic
Ruby in Zoisite with Hornblende
Anyolite (Ruby: Al2O3, Zoisite: Ca2Al3(SiO4)3(OH))
metamorphic
Garnet Schist or Garnet-bearing Quartzite
Metamorphic rock containing Almandine Garnet (Fe3Al2(SiO4)3) and Quartz (SiO2)
metamorphic
Almandine Garnet in Schist
Almandine Garnet (Fe3Al2(SiO4)3) in Mica Schist
metamorphic
Diorite (River Pebble)
Intermediate Phaneritic Igneous Rock
igneous
Diorite (possibly fine-grained variety or a related intermediate intrusive rock like a felsic gabbro or a dark granodiorite)
Diorite (Igneous rock, intrusive, intermediate composition)
Igneous Rock
Green Aventurine
Quartz (Silicon Dioxide, SiO2) with fuchsite inclusions
mineral
Carnelian
Carnelian (Cryptocrystalline Quartz, SiO2)
mineral
Green Aventurine
Silicon Dioxide (Quartz with Fuchsite inclusions), SiO2
mineral
Rough Quartz (Clear Quartz)
Silicon Dioxide (SiO2)
mineral
Yellow Agate
Chalcedony (cryptocrystalline silica), SiO2
mineral
Amethyst Geode
Amethyst (Silicon Dioxide), Formula: SiO2
mineral
Quartz with Chalcopyrite and Pyrite
Silicon Dioxide (SiO2) with Copper Iron Sulfide (CuFeS2)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions
mineral
Granite
Felsic intrusive igneous rock
igneous
Gneiss (specifically a weathered or stream-worn specimen)
Gneiss (Foliated Metamorphic Rock)
metamorphic
Gneiss
Gneiss
metamorphic
Rhyolite
Extrusive igneous rock (felsic)
igneous
Amphibolite with Hornblende
Amphibole-rich Metamorphic Rock (Ca2(Mg,Fe)5Si8O22(OH)2)
metamorphic
Glacial granite/granitoid boulder
Granite to granodiorite; chiefly quartz, feldspar, and biotite/hornblende
igneous
Gravel / Limestone Fragment
Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock
sedimentary
Granite
Felsic intrusive igneous rock
igneous
Granite Pebble
Intrusive Igneous Rock (Quartz, Feldspar, Mica)
igneous
Pegmatite or Graphic Granite
Intrusive Igneous Rock
igneous
Porphyry
Porphyritic Igneous Rock
igneous
Chalcedony (Botryoidal Agate vein)
Chalcedony (Microcrystalline Quartz) - SiO2
mineral
Carnelian
Carnelian (Cryptocrystalline variety of Quartz, SiO2)
mineral
Gold in Quartz Matrix
Native Gold (Au) in Quartz (SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenite (lithic or quartz sandstone)
sedimentary
Granite
Granite (a felsic intrusive igneous rock)
Igneous Rock
Gneiss
Gneiss
metamorphic
Sandstone (likely Arkosic or Lithic Sandstone)
Arenite (composed primarily of SiO2 with various lithic fragments)
sedimentary
Fossilized oyster or bivalve shell
Fossil Gryphaeidae or Ostreoidea; calcitic shell, CaCO₃
fossil