Eclogite
Eclogite (Pyrope garnet and Omphacite pyroxene)
metamorphic
Category
Organic (Non Rock)
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Dark river-worn pebble, likely basalt
Basalt (fine-grained mafic volcanic rock; identification from the image is approximate)
igneous
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Rounded dark pebble, possibly weathered basalt
Fine-grained mafic volcanic rock; likely basalt, but identification is uncertain from the photograph
igneous
River Rock (likely Siltstone or fine-grained Sandstone)
Clastic Sedimentary Rock
sedimentary
Quartzite Cobble
Quartzite (principally SiO2)
metamorphic
Green Glass Slag
Amorphous Silicon Dioxide (SiO2) with metal oxide impurities
mineraloid (man-made)
Petrified Bone (Fossil Bone)
Per mineralization fossil bone (varies by organism, predominantly replacement by SiO2 - Quartz/Chalcedony)
fossil
Granite
Granite (quartz–feldspar intrusive igneous rock)
igneous
Shale (or Slate / Coal / Jet)
Laminated fine-grained sedimentary rock (predominantly clay minerals)
sedimentary
Microcrystalline Quartz (Chert/Agate)
Silicon Dioxide (SiO2)
sedimentary
Chert Nodule / Ironstone Concretion
Microcrystalline Quartz (SiO2) with Iron Oxides
sedimentary
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Fossiliferous Rock (Invertebrate Fossil in Matrix)
Fossiliferous limestone or shaly matrix containing skeletal fossil remains
fossil
Green aventurine (likely)
Quartzite dominated by quartz (SiO₂), colored green by fuchsite mica or chlorite
mineral
Granite Cobble
Granite (Porphyritic/Coarse-grained)
igneous
Fossil Shell Fragment (possibly Brachiopod or Bivalve)
Calcium Carbonate (CaCO3) - Phylum Brachiopoda or Mollusca
sedimentary
Fossiliferous Limestone
Biogenic Limestone (Calcium Carbonate, CaCO3)
sedimentary
Shale
Mudstone (composed primarily of clay minerals like kaolinite, illite, and smectite, with quartz and calcite)
sedimentary
Gravel / Limestone Fragment
Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock
sedimentary
Quartzite (Orthoquartzite)
SiO2 (Silicon Dioxide) with Iron Oxide inclusions
metamorphic
Ironstone Nodules in Chalk/Limestone
Limonite/Goethite concretions (FeO(OH)·nH2O) in Calcium Carbonate matrix (CaCO3)
sedimentary
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
mineral
Quartzite River Rock
Metamorphic Rock (Recrystallized Quartz - SiO2)
metamorphic
Quartzite
Quartzite (SiO2-rich metamorphic rock)
metamorphic
Herkimer Diamond
Quartz (Silica - SiO2)
mineral
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Quartzite
Quartzite (primarily SiO2)
metamorphic
Fossilized Brachiopod
Brachiopoda (Phylum)
fossil
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Quartzite
Quartzite (SiO2-rich metamorphic rock)
metamorphic
Anthracite Coal
Anthracite (Carbon-based metamorphic rock)
metamorphic
Limestone Pebble
Sedimentary Rock (Calcite, CaCO3)
sedimentary
Green Slag Glass
Cullet (Amorphous Silicon Dioxide with impurities)
Man-made rock-like material
Quartzite
Metamorphic Rock (Mainly SiO2)
metamorphic
Granite
Granite (Plutonic Igneous Rock)
igneous
Granite
Granite (Felsic Plutonic Rock)
igneous
Fossilized Bone
Permineralized Vertebrate Bone
fossil
Fossil Skin Impression
Tegumentary fossil imprint in sedimentary ironstone
fossil
Geode with Quartz Crystal Cavity
Silicon Dioxide (SiO2) in Calcareous/Siliceous Matrix
sedimentary