Andesite Porphyry
Andesite (extrusive volcanic rock)
igneous
Category
Rock (Likely Sedimentary)
Browse rock (likely sedimentary) specimens identified by the Rock Identifier community.
Chert (Flint)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide) - SiO2
mineral
Orange Calcite
Calcite (Calcium Carbonate, CaCO3)
mineral
River Cobble (likely Basalt or Chert)
Siliceous River Rock / Microcrystalline Quartz / Mafic Igneous
igneous/sedimentary
Granite Pebble
Felsic Plutonic Rock (primarily Quartz, Feldspar, and Mica)
igneous
Jasper with Hematite Inclusions
Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3)
sedimentary
Chert (Common Opal/Agate inclusion)
Microcrystalline Quartz (SiO2)
sedimentary
Quartzite Pebble (with Iron Inclusions)
Quartzite (primarily SiO2 with Fe2O3/FeOOH impurities)
metamorphic
Milky Quartz (with Iron Oxide staining)
Quartz (Silicon Dioxide - SiO2)
mineral
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
mineral
Mica Schist with Iron Staining
Muscovite/Biotite Schist
metamorphic
River Rock (likely Quartzite or Chert)
Quartzite (primarily SiO2)
metamorphic
Mudstone
Lutylite (group of fine-grained sedimentary rocks)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Jasper Quarzite (possibly Lake Superior Agate mix)
Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)
sedimentary
Granite (Core Sample)
Phaneritic Felsic Igneous Rock (Granite)
igneous
Slate
Foliated Metamorphic Rock (Mainly composed of Quartz, Illite, Chlorite)
metamorphic
Granite Cobble
Plutonic Igneous Rock (Granitic)
igneous
Chalcedony (Carnelian/Agate variety)
Silicon Dioxide (SiO2) with trace hematite/iron impurities
mineral
Petrified Wood
Silicified Wood (primarily SiO2)
metamorphic
Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Banded Chert (Jasper)
Silicon Dioxide (SiO2)
sedimentary
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
sedimentary
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Mineral
Chert (Common Variety)
Cryptocrystalline Quartz (SiO2)
sedimentary
Yellow Quartzite (Iron-stained)
Quartzite (primarily SiO2 with Fe2O3 staining)
metamorphic
Granite
Phaneritic plutonic rock (SiO2 range 65-75%)
igneous
Granitoid (Granite/Granodiorite)
Plutonic igneous rock (variable composition, primarily SiO2)
igneous
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary
Fossil Shark Tooth (Cretaceous white shark type)
Squalicorax (commonly known as Crow Shark)
Organic specimen (fossil)
Sandstone (Ferruginous)
Arenite (Siliclastic Sedimentary Rock)
sedimentary
Quartz Crystal Cluster
Silicon Dioxide (SiO2)
mineral
Basalt with Quartz Vein and Weathering Crust
Amygdaloidal or Porphyritic Basalt
igneous
Banded Gneiss (with possible weathered sulfide or iron staining)
Gneiss, potentially with iron oxide/hydroxide staining (e.g., limonite) or weathered sulfides
Metamorphic
Obsidian (Arrowhead Lithic Tool)
Obsidian (Amorphous Volcanic Glass / SiO2 + inclusions)
igneous
Quartz (Crystal/Druzy Quartz)
Quartz (SiO₂)
Mineral
Yellow Chert (Microcrystalline Quartz)
Chert / SiO2 (Silicon Dioxide)
sedimentary
Demitasse Granite (Diorite-Granite transition)
Intermediate Plutonic Rock (Granodiorite/Diorite mix)
igneous