Basalt
Basalt (Mafic volcanic rock)
igneous
Category
Man Made (Synthetic Rock)
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Basalt River Cobble
Basalt (Mafic volcanic rock)
igneous
Basalt Cobble
Aphanitic Mafic Igneous Rock (Basalt)
igneous
Shale
Fissile Mudstone (primarily composed of phyllosilicate minerals like kaolinite, montmorillonite, and illite)
sedimentary
Milky Quartz Pebble with Iron Inclusions
Silicon Dioxide (SiO2)
mineral
Granite Pebble
Granite (Plutonic Igneous Rock)
igneous
Granite Pebble (Pegmatitic Quartz-Feldspar River Rock)
Granite / Quartz-Feldspar-Mica Aggregate
igneous
Sandstone with Desert Varnish
Arenite (SiO2 predominantly) with Ferromanganese coating
sedimentary
Generic Pebble
Lithic Fragment
sedimentary
Quartz Vein in Amphibolite / Gneiss
Quartz (SiO2) in Mafic Metamorphic Host Rock
metamorphic
River Rock / Stream Pebble
Fluvial Clast / Rounded Sedimentary Particle
Sedimentary Rock (possibly composed of various minerals)
Copper Ore / Altered Granodiorite
Cupriferous rock with silicate gangue
mineral
Basalt
Extrusive mafic igneous rock
igneous
Gossan (with Limonite/Hematite coating)
Ferruginous Gossan (Fe2O3·nH2O / Fe2O3)
sedimentary
Red Sandstone
Arenite (primarily quartz with iron oxide cement)
sedimentary
Basalt Pebble
Extrusive Igneous Rock
igneous
Sedimentary Rock (Limestone or Siltstone pebble)
Sedimentary rock fragment
sedimentary
Rounded quartz-rich pebble
Chert or quartzite pebble (tentative; mostly microcrystalline quartz, SiO₂)
sedimentary
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Sandstone
Quartz Sandstone (predominantly)
Sedimentary
Magnetic Hematite
Magnetized Hematite (an iron oxide mineral, Fe2O3, that has undergone magnetization)
Mineral
Sandstone
Arenite (primarily SiO2)
sedimentary
Vesicular Basalt (Lava Rock)
Vesicular Basalt
igneous
Basalt
Basalt (Mafic Extrusive)
igneous
Sandstone (Weathered Cobble)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Granite
Phaneritic plutonic rock (primarily Quartz, Feldspar, and Mica)
igneous
Xenolith in Basalt
Mafic Igneous Rock with Felsic Inclusion
igneous
Veined Limestone (Micrite) with Quartz/Calcite Veins
Calcium Carbonate (CaCO3) with Silicate or Carbonate inclusions
sedimentary
Geode
Quartz nodule / Chalcedony-lined cavity
sedimentary
Porphyritic Basalt
Porphyritic Basalt with Plagioclase Phenocrysts
igneous
Serpentine
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
metamorphic
Serpentine
Antigorite, Lizardite, or Chrysotile (Mg3Si2O5(OH)4)
metamorphic
Granite Pebble
Intrusive Igneous Rock
igneous
Sandstone (with Rock Art)
Sandstone (Clastic Sedimentary Rock)
sedimentary
Granite Pebble
Granite (Plutonic Igneous Rock)
igneous
Quartzite Pebble (Stream-rounded Quartz/Quartzite Gravel)
Quartzite / Silicon Dioxide (SiO2)
metamorphic
Agate (specifically, multi-colored or pastel-dyed agate)
Silicon dioxide (SiO2) - specifically, a cryptocrystalline variety of quartz known as Chalcedony, with banding classified as Agate. (If it were Fluorite, the chemical formula would be Calcium Fluoride - CaF2).
Mineral
Red Sandstone
Sedimentary Arenite / Quartzose Sandstone
sedimentary
Granite
Granite (Felsic Plutonic Rock)
igneous
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
River Pebble (Granite/Gneiss)
Granitic Pebble / Quartz-Feldspar Aggregate
igneous
River Pebble (Siltstone / Fine-grained Sandstone)
Sedimentary Pebble (Siliclastic)
sedimentary