Conglomeratic gravel / lithified alluvial deposit
Polymictic conglomerate or pebble-rich sandstone (likely weakly cemented)
sedimentary
Category
Not A Rock
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Blue-gray quartz-rich rock, possibly blue aventurine or sodalite-bearing stone
Probable quartz–feldspar aggregate; exact identification requires testing
mineral
Dark gray fine-grained rock fragment
Likely basalt (possibly andesite); exact identification is limited by the photograph
igneous
Serpentine (Serpentinite)
Serpentinite / (Mg,Fe)3Si2O5(OH)4
metamorphic
Rounded gray river pebble, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene, possibly olivine)
igneous
Quartzite River Stone
Quartzite (SiO2)
metamorphic
Geode
Quartz / Chalcedony nodule
sedimentary
Mudstone
Argillite
sedimentary
Ferrous Slag (Iron Smelting By-product)
Fused Siliceous Slag
Anthropogenic Material (Man-made Rock)
Sandstone (Painted)
Arenite (primarily SiO2)
sedimentary
Quartzite Pebble
Metamorphic Quartzite (SiO2)
metamorphic
Gneiss (Pebble)
Gneiss
metamorphic
Brecciated Jasper
Silicon Dioxide (SiO2) with Hematite impurities
sedimentary
Chert (Yellow/Tan Variety)
Chert (SiO2)
sedimentary
Serpentine (Serpentinite)
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Vesicular Basalt
Extrusive mafic igneous rock
igneous
Grey Limestone Pebble
Limestone (Calcium Carbonate - CaCO3)
sedimentary
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Slate with Quartz Vein
Foliated Metamorphic Rock (Mainly Quartz, Muscovite, Chlorite)
metamorphic
Sandstone
Sandstone (composed predominantly of Quartz, SiO2)
sedimentary
Red Scoria
Scoria (Vesicular Basalt/Andesite)
igneous
Vesicular Basalt (Scoria)
Aphanitic Mafic Igneous Rock (Vesicular Basalt)
igneous
Tumbled amber-colored agate or chalcedony
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/agate
mineral
Rounded quartz-rich river pebble
Lithic clast, likely quartzite or fine-grained sandstone
sedimentary
Rounded quartz-rich pebble
Chert or quartzite pebble (tentative; mostly microcrystalline quartz, SiO₂)
sedimentary
Quartz Crystal Cluster on Matrix
Silicon Dioxide (SiO2)
mineral
Agate
Silicon Dioxide (SiO2) - variety Chalcedony
mineral
Agate (specifically a Yellow/Honey Agate)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Quartz Crystal on Matrix
Silicon Dioxide (SiO2)
mineral
Quartz Vein in Host Rock
Hydrothermal Quartz (SiO2) in Slates/Schists
metamorphic
Brecciated quartz vein rock
Quartz (SiO₂), with iron-oxide staining and likely feldspar/carbonate gangue
mineral
Conglomerate
Conglomerate rock
sedimentary
Conglomerate
Conglomerate rock
sedimentary
Conglomerate
Conglomerate rock
sedimentary
Sandstone or Limestone
Sedimentary Rock
Sedimentary
Shale
Fissile mudrock (composed of clay-sized particles and detrital grains)
sedimentary
Limestone
Sedimentary Calcium Carbonate (CaCO3)
sedimentary
Druzy Quartz on Chert/Siltstone
Silicon Dioxide (SiO2) on Microcrystalline Silica/Siltstone matrix
sedimentary
Sandstone (with Iron Staining)
Clastic sedimentary rock (SiO2 with Fe2O3 oxides)
sedimentary
Quartz vein in weathered host rock
Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix
mineral
Banded Gneiss
Gneiss (Metamorphic Rock)
metamorphic
Mixed Rock and Mineral Collection
Various geological specimens
igneous, sedimentary, and metamorphic