Crinoid Fossil in Limestone
Crinoid (Class Crinoidea) in Fossiliferous Limestone (CaCO3)
sedimentary
Category
Rock
Browse rock specimens identified by the Rock Identifier community.
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Limonite (Iron Ore)
Goethite and related iron hydroxides (FeO(OH)·nH2O)
mineral
Basalt Porphyry
Porphyritic Basalt
igneous
Asphalt (Bituminous Concrete)
Bituminous mix / Anthropogenic conglomerate
man-made composite (lithified equivalent of sedimentary)
Basalt
Basalt (principally Plagioclase and Pyroxene)
igneous
Sandstone (Pebble/Cobble)
Sandstone (arenite is a more precise term for sandstone with less than 15% matrix; this specimen appears to be a lithic or quartz arenite)
Sedimentary
Sandstone
Arenite (predominantly Quartz Sandstone)
sedimentary
Basalt River Stone
Aphanitic Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
igneous
Basalt (Stream-worn Cobble)
Mafic Igneous Rock (primarily Plagioclase and Pyroxene)
igneous
Sandstone
Clastic sedimentary rock (primarily SiO2)
sedimentary
Basalt with Epidote Veins
Mafic Igneous Rock (Basalt)
igneous
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Serpentinite (Serpentine Rock)
Primarily composed of serpentine group minerals, such as antigorite, chrysotile, and lizardite. Chemical formula for serpentine minerals is (Mg,Fe)3Si2O5(OH)4.
Metamorphic
Quartz on Greenstone
Silicon Dioxide (SiO2) on Altered Igneous Geologic Unit
metamorphic
Sandstone
Arenite (SiO2 primarily)
sedimentary
Quartz (Pebble)
Quartz (SiO₂)
Mineral
Rose Quartz
Silicon Dioxide (SiO2)
mineral
Jasper with Quartz inclusions
Silicon Dioxide (SiO2) with impurities
sedimentary
Jasper with Quartz Veining
Silicon Dioxide (SiO2) - Opaque cryptocrystalline variety of Quartz
sedimentary
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
mineral
Mixed Tumbled Gemstones and River Rocks
Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)
Mixed (Igneous, Sedimentary, Metamorphic, and Minerals)
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone (with Lichen)
Arenite (composed primarily of SiO2)
sedimentary
Scoria (with likely iron oxidation)
Scoria (Basaltic Scoria)
igneous
River Pebbles and Quartz
Mixed Igneous, Sedimentary, and Metamorphic Rocks (Silicon Dioxide SiO2 dominant)
mixed
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
metamorphic
Quartzite Pebble (River Rock)
Quartzite (mainly SiO2)
metamorphic
Sandstone (with Iron Staining)
Clastic sedimentary rock (SiO2 with Fe2O3 impurities)
sedimentary
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)
sedimentary
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Sandstone (Quartzose Sandstone)
Clastic Terrigenous Sedimentary Rock (primarily SiO2)
sedimentary
Sandstone (Weathered)
Arenite (primarily SiO2)
sedimentary
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Granite Cobble
Plutonic Igneous Rock (Granitic)
igneous
Jasper (Yellow/Brown variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Sandstone
Arenite
sedimentary
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
mineral
Yellow Jasper
Silicon Dioxide (SiO2) - Impure Cryptocrystalline Quartz
sedimentary
Quartz Vein in Host Rock (Gabbro or Basalt)
Silicon Dioxide (SiO2) with Mafic Silicates
metamorphic/igneous
Sandstone (Quartz-rich)
Arenite (composed mainly of SiO2)
sedimentary
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary