River Pebble (Gravel)
Clastic sedimentary rock (likely Siltstone or Mudstone pebble; SiO2 with various impurities)
sedimentary
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Diorite
Diorite (Intermediate intrusive igneous rock)
igneous
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Banded Slate
Slate (Metamorphosed Siltstone/Mudstone)
metamorphic
Weathered granite (likely)
Granite, a quartz–feldspar–mica intrusive igneous rock
igneous
Weathered granitic or gneissic cobble
Likely altered granite/granodiorite; exact identification requires a fresh surface and testing
igneous
Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins
Quartz-veined metamorphic rock (Silicate mineral assemblage)
metamorphic
Green serpentine (likely serpentine-rich stone)
Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; composition approximately Mg₃Si₂O₅(OH)₄
metamorphic
Banded gneiss pebble
Gneiss, commonly quartz–feldspar–mica gneiss
metamorphic
Granite
Phaneritic Igneous Rock (Granite)
igneous
Druzy Quartz on Sandstone
Silicon Dioxide (SiO2) with Quartz Crystals on Clastic Sedimentary Rock
sedimentary
Eroded Brick or Pumice-like Scoria
Vesicular Basalt / Scoria (Anthropogenic variant: Eroded Firebrick)
igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
igneous
Granite
Intrusive Igneous Rock
igneous
Sandstone (Micaceous)
Clastic Sedimentary Rock (primarily SiO2 with Mica)
sedimentary
Sandstone
Arenite
sedimentary
Quartz Vein Rock
Quartz (Silicon Dioxide, SiO2)
igneous
Granite
Intrusive Igneous Rock
igneous
Sandstone
Arenite (primarily SiO2)
sedimentary
Painted River Rock
Artificially Coated Sedimentary Rock
sedimentary
Quartz with Chlorite inclusions
SiO2 with (Mg,Fe)3(Si,Al)4O10(OH)2⋅(Mg,Fe)3(OH)6
mineral
Green Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Unknown Rock Specimen
igneous
Sedimentary Rock with Crafts (Pet Rock)
Sedimentary rock decorated with synthetic materials
sedimentary
Polished river pebble
Indeterminate; likely fine-grained quartz-rich sedimentary rock or weathered volcanic rock
sedimentary
Shale or Slate with Quartz Veins
Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins
Metamorphic, likely Sedimentary with Quartz veins
Sandstone with Quartz Vein
Arenite with Crystalline Silica (SiO2)
sedimentary
Small rounded pebble, likely basalt
Fine-grained mafic volcanic rock (likely basalt); image alone cannot confirm composition
igneous
Granite
Granite
igneous
Andesite Porphyry
Andesite Porphyry
Igneous
Likely weathered basalt or andesite fragment
Fine-grained volcanic rock, likely basaltic-andesite; exact identification requires testing
igneous
Basalt
Extrusive Igneous Rock
igneous
Basalt Pebble
Extrusive Igneous Rock
igneous
Shale
Clastic Sedimentary Rock
sedimentary
Rounded gray stone, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; likely basalt (plagioclase ± pyroxene, possibly olivine)
igneous
Basalt
Basalt (Mafic volcanic rock)
igneous
Sandstone
Clastic sedimentary rock (primarily SiO2)
sedimentary
Basalt with Granite Inclusions (Xenoliths)
Mafic igneous rock (Basalt) with Sialic minerals
igneous
Quartz-veined Mudstone or Argillite
SiO2 (Quartz) in Siltstone/Mudstone matrix
sedimentary
River Pebble (Quartzite or Chert)
Silicon Dioxide (SiO2)
metamorphic or sedimentary
Basalt
Basalt (Aphanitic-fine grained mafic igneous rock)
igneous
Rounded quartz-rich pebble
Lithic pebble; likely quartz/quartzite with iron-oxide staining
sedimentary