Basalt with Quartz Vein
Extrusive Igneous Rock / Volcanic Rock
igneous
Category
Not A Rock
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Smooth river pebble, likely quartz-rich sandstone or quartzite
Probable quartz arenite (sandstone) or quartzite; mainly SiO₂ with minor iron-bearing minerals
sedimentary/metamorphic
Sandstone (with Rock Art)
Sandstone (Clastic Sedimentary Rock)
sedimentary
Quartzite (Yellow/Orange variety)
Quartzite (primarily SiO2)
metamorphic
River Rock
Mixed lithology clast
sedimentary
Porphyry
Porphyritic igneous rock
igneous
Basalt with Alteration Crust
Basalt (SiO2 range 45-52%)
igneous
Leopard Skin Jasper
Orbicular Jasper (Silicon Dioxide, SiO2)
sedimentary
Basalt
Mafic Igneous Rock (composed primarily of plagioclase feldspar and pyroxene)
Igneous
Basalt
Mafic extrusive igneous rock
igneous
Clear Quartz (Cut/Faceted Gemstone)
Silicon Dioxide (SiO2)
gemstone
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Basalt
Basalt (Mafic volcanic rock)
igneous
Basalt Cobble
Aphanitic Mafic Igneous Rock (Basalt)
igneous
Basalt River Cobble
Basalt (Mafic volcanic rock)
igneous
Milky Quartz with Chlorite Schist Inclusions
Quartz (SiO2) with Chlorite Group silicates (typically (Mg,Fe)3(Si,Al)4O10(OH)2)
metamorphic
Granite
Phaneritic Igneous Rock (primarily Quartz, Feldspar, Mica)
igneous
Small red-brown mineral or rock fragment
Unidentified; possibly iron-oxide-rich jasper, garnet, or weathered sulfide
mineral
Granite River Rock
Intrusive igneous rock (composed mainly of quartz, alkali feldspar, and plagioclase)
igneous
River-worn Chert
Microcrystalline Quartz (SiO2)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz Pebble (Feldspathic / Chert Pebble)
Silicon Dioxide (SiO2) / Potassium Feldspar (KAlSi3O8)
sedimentary
Sandstone (River Cobble)
Sandstone (principally composed of Quartz, SiO2)
sedimentary
Pebble (likely Sandstone or Granitic Pebble)
Clastic Sediment (or specific rock type, e.g., Arenite, Granitoid Pebble)
Rock (likely Sedimentary)
Pink granite pebble
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Rounded granitic gneiss pebble
Quartz–feldspar–biotite gneiss (tentative; exact identification requires closer inspection)
metamorphic
Granite-like cobble
Granitoid, likely biotite granite or granodiorite
igneous
Porphyritic granite (likely orbicular/porphyritic granitoid)
Quartz–feldspar granitoid; commonly composed of K-feldspar, plagioclase, quartz, and biotite/hornblende
igneous
Likely silver-gray granite or granitic gneiss fragment
Granite; primarily quartz (SiO₂), feldspar, and mica (exact identification uncertain from image)
igneous
Quartz Druzy (Geode Fragment)
Silicon Dioxide (SiO2)
mineral
Quartz-veined Metamorphic Pebble
Silicate-rich metamorphic rock with quartz veins (SiO2)
metamorphic
Quartz Vein in Metamorphic Rock
Quartzite or Schist host with Quartz (SiO2) intrusion
metamorphic
Wishing Rock (Quartz Vein in Host Rock)
Silicon dioxide (SiO2) vein in various host rocks
Igneous/Sedimentary/Metamorphic with Mineral Vein
Yellow Agate (Banded Chalcedony)
Silicon Dioxide (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2) within a sedimentary or volcanic shell
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
River Pebble (Siltstone / Fine Sandstone)
Sedimentary Rock (siliciclastic clastic rock)
sedimentary
Basalt with Weathering Rind
Basalt (Mafic Volcanic Rock)
igneous
Tumbled yellow jasper (probable)
Jasper, an opaque microcrystalline variety of quartz; chiefly SiO₂ with iron-oxide inclusions
mineral
Greenstone pebble (likely altered basalt or serpentine)
Greenschist-facies mafic rock; commonly chlorite–actinolite–epidote ± serpentine
metamorphic
Vesicular Basalt (or Scoria)
Vesicular Basalt
igneous
Shale / Mudstone
Laminated Mudrock (Siliciclastic Sedimentary Rock)
sedimentary