Quartz Druzy on Agate (River Cobble)
Silicon Dioxide (SiO2)
Mineral / Sedimentary (often associated with volcanic hosts)
Category
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Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Granite
Plutonic Granite
igneous
Sandstone (with Iron Staining)
Arenite (Silicon Dioxide, SiO2, often with iron oxides like Limonite)
sedimentary
Blue Dyed Agate
Silicon Dioxide (SiO2) with artificial pigment
mineral
Amethyst (Tumbled)
Quartz (Silicon Dioxide, SiO2) with iron impurities
mineral
Sandstone (likely Arkosic or Lithic)
Clastic Sedimentary Rock (SiO2 with accessory minerals)
sedimentary
Sandstone
Clastic Sedimentary Rock (primarily SiO2)
sedimentary
Granite
Granite (Phaneritic Quartz Monzonite)
igneous
Granite
Granite (Phaneritic Igneous Rock)
igneous
Pink Granite
Phaneritic Felsic Igneous Rock
igneous
Granite
Granite (Felsic Plutonic Rock)
igneous
Granite
Felsic Intrusive Igneous Rock
igneous
Smoky Quartz
Silicon Dioxide (SiO2)
mineral
Red Sandstone
Quartzose Sandstone (primarily quartz grains cemented by iron oxides)
sedimentary
Copper slag or vesicular basalt with copper minerals
Industrial slag / Basaltic matrix with secondary copper minerals
igneous
Sandstone
Sedimentary Rock (Quartz arenite)
sedimentary
Flagstone
Sedimentary Sandstone / Flagstone
sedimentary
Sandstone (Arkose/Quartzose)
Arenite (SiO2 based clastic rock)
sedimentary
Porphyritic Basalt (Porphyry pebble)
Porphyritic Basalt / Amygdaloidal Basalt
igneous
Sandstone
Arenite (primarily SiO2 - Silicon Dioxide)
sedimentary
Shale with Iron Oxide Staining
Fissile Mudstone (primarily clay minerals and quartz)
sedimentary
Tumbled gray feldspar-rich stone, possibly granite or quartzite
Indeterminate; likely quartz–feldspar aggregate, potentially fine-grained granite or quartzite
igneous
Sandstone (Pebble)
Sandstone (composed mainly of Quartz, SiO2, with feldspar and lithic fragments)
sedimentary
Quartz (Rose Quartz / Quartz Pebble)
Silicon Dioxide (SiO2)
mineral
Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
mineral
Granite
Granite (Phaneritic Quartz-Feldspar rock)
igneous
Granite
Granite (High-silica plutonic rock)
igneous
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2 + Fe2O3)
mineral
Sandstone (with Iron Staining)
Clastic sedimentary rock (SiO2 with Fe2O3 impurities)
sedimentary
Pink Granite River Rock
Phaneritic Felsic Igneous Rock (Granite)
igneous
Granite (River-worn pebble)
Phaneritic plutonic rock (SiO2 + Al2O3)
igneous
Speckled rounded stone, likely granite or granitic gneiss
Granite/granitic gneiss; primarily quartz (SiO₂), feldspar, and dark mica or amphibole
igneous
River Pebble (Siltstone / Fine Sandstone)
Sedimentary Rock (siliciclastic clastic rock)
sedimentary
Sandstone
Arenite (specifically Iron-stained Quartz Sandstone)
sedimentary
Herkimer Diamond
Quartz (Silicon Dioxide, SiO2)
mineral
River Stone (likely Quartzite or Chert)
Sedimentary rock composed of Silicon Dioxide (SiO2)
sedimentary
Blue Lace Agate (Heat-treated/Crackle Quartz variety)
Silicon Dioxide (SiO2)
mineral
Agate (Polished Nodule)
Agate (Silicon Dioxide, SiO2)
mineral
Beach Pebble Quartzite / Chalcedony Pebble
Silicon Dioxide (SiO2)
metamorphic
Chert (Jasper / Quartz pebble)
Microcrystalline Quartz (SiO2)
sedimentary