Basalt (Porphyritic Basalt)
Extrusive Igneous Rock
igneous
Category
Not A Rock
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Serpentine
Antigorite/Lizardite/Chrysotile group, Mg3Si2O5(OH)4
metamorphic
Pink Granite
Phaneritic Felsic Igneous Rock (composed primarily of Quartz and Potassium Feldspar)
igneous
Basalt
Basalt (Mafic Extrusive)
igneous
Hag Stone (Adder Stone / Geode-bearing Pebble)
Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)
sedimentary
Quartz vein in host rock
Milky quartz (SiO₂) with likely metamorphic country rock, possibly gneiss or schist
metamorphic
Pumice and Scoria
Vesicular Volcanic Rock (Pumice: Silicic / Scoria: Mafic)
igneous
Basalt
Basalt (composition predominately Plagioclase feldspar and Pyroxene)
igneous
Dark basalt cobble
Basalt, a fine-grained mafic volcanic rock
igneous
Basalt (Greenstone/Water-worn Pebble)
Basalt (containing Chlorite/Epidote)
igneous
Fossilized Bone
Permineralized Vertebrate Bone
fossil
Asphalt aggregate
Human-made bituminous asphalt containing crushed silicate rock aggregate
sedimentary
Painted Sandstone
Sandstone (clastic sedimentary rock) with acrylic/artistic coating
sedimentary
Rugose Coral Fossil
Order Rugosa
fossil
Likely weathered granite or granitic pegmatite fragment
Granite; primarily quartz (SiO₂), feldspar, and mica
igneous
Weathered Sedimentary Rock
Sedimentary Rock
Sedimentary
Rounded quartz-rich river pebble
Likely quartz-bearing rock; exact lithology cannot be determined from the photograph
igneous
Weathered iron-rich rock (possibly ironstone)
Indeterminate ferruginous rock; likely iron-oxide-cemented sandstone or ironstone
sedimentary
Sandstone (with potentially high Feldspar/Arkose content)
Clastic sedimentary rock (SiO2 dominated)
sedimentary
River Rock / Stream Pebble
Fluvial Clast / Rounded Sedimentary Particle
Sedimentary Rock (possibly composed of various minerals)
Basalt
Mafic extrusive igneous rock
igneous
Weathered granite
Granite; quartz–feldspar–mica plutonic rock
igneous
Weathered granite
Granite; interlocking quartz, feldspar, and mica minerals
igneous
Sandstone
Arenite
Sedimentary
Polished brecciated jasper
Jasper, an opaque microcrystalline variety of chalcedony (SiO₂), with iron-oxide staining
mineral
Sandstone Pebble / Quartzite Pebble
SiO2 (Silicon Dioxide enriched sedimentary rock)
sedimentary
Weathered limestone or calcareous sandstone
Calcitic carbonate rock, likely limestone (CaCO₃), possibly slightly dolomitic
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Banded Greywacke
Greywacke (Lithic wacke)
sedimentary
Granite
Intrusive Igneous Rock
igneous
Granite Cobble
Intrusive Igneous Rock (Felsic to Intermediate)
igneous
Basalt
Extrusive Igneous Rock
igneous
Basalt
Extrusive Igneous Rock
igneous
Dyed Quartzite
Metamorphosed Quartz (SiO2) with synthetic pigment
metamorphic
Granite
Plutonic felsic rock (Quartz, Feldspar, Mica)
igneous
Basalt
Extrusive mafic igneous rock
igneous
Slate
Foliated Metamorphic Rock (Mainly composed of Quartz, Illite, Chlorite)
metamorphic
Iron-stained quartz-rich rock (possibly ironstone)
Quartz (SiO₂) with iron-oxide/hydroxide staining, likely limonite/goethite
mineral
Fossil Shell
Invertebrate fossil (Mollusca)
fossil
Weathered granite
Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspars, and mica
igneous
Ironstone Concretion (Ironstone Gourd)
Limonite/Goethite Concretion (FeOO(H))
sedimentary