Quartzite with Gneissic Banding
Quartzite (primarily SiO2) with mafic mineral inclusions
metamorphic
Category
Mineral, Often A Rock Given Its Aggregate Nature
Browse mineral, often a rock given its aggregate nature specimens identified by the Rock Identifier community.
Ferruginous Sandstone (Gerrit)
Arenite with Iron Oxide cementation
sedimentary
Agate (Moss or Dendritic Agate)
Chalcedony (Silicon Dioxide, SiO2)
mineral
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Sedimentary
Quartz (specifically Quartzite or Massive Quartz)
Silicon Dioxide (SiO2)
Mineral
Chert (or Flint)
Chert (Sedimentary Cryptocrystalline Sio2)
sedimentary
Granite Sand (Decomposed Granite)
Grus / Quartz-Feldspar Detritus
sedimentary
Basalt
Mafic volcanic rock (formula varies by mineral content: Ca-plagioclase, Pyroxene, Olivine)
igneous
Gneiss (specifically Micaceous Gneiss)
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Quartz Geode
Quartz (Silicon Dioxide - SiO2) within a Chalcedony and Limonite shell
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Basalt Beach Pebble
Basalt (Aphanitic Mafic Volcanic Rock)
igneous
Basalt River Stones
Aphantic Mafic Igneous Rock (Basalt)
igneous
Agate (Lace Agate Geode Slice)
Silicon Dioxide (SiO2)
mineral
Specular Hematite
Specularite (Fe2O3)
mineral
Ethiopian Fire Opal
Hydrated Silica (SiO2·nH2O)
mineral
Granodiorite
Granodiorite (containing Quartz, Plagioclase, Orthoclase, Biotite/Hornblende)
igneous
Quartz
Silicon dioxide (SiO2)
Mineral
Emerald in Matrix
Beryl (Be3Al2Si6O18) with trace amounts of Chromium/Vanadium
mineral
Quartz (Druzy or Crystalline variety)
Silicon Dioxide (SiO2)
mineral
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
igneous
Granite
Granite (composed mainly of Quartz, Feldspar, and Mica)
igneous
Sandstone (likely Ferruginous)
Sandstone (SiO2 with iron oxides)
sedimentary
Shale
Fissile Clay-dominant Mudrock (SiO2, Al2O3, K2O, Na2O, CaO, MgO)
sedimentary
River Rock (Basalt)
Aphanitic Basaltic Rock
igneous
Sandstone (with Limonite staining)
Arenite (primarily SiO2 with FeO(OH)·nH2O)
sedimentary
Granite featuring Quartz Vein
Granite with hydrothermal silica (SiO2) intrusion
igneous
Granite
Phaneritic Plutonic Rock (primarily Quartz, Feldspar, and Mica/Amphibole)
igneous
Agate (specifically Carnelian Agate or Lake Superior style Agate)
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Green Aventurine
Aventurine Quartz (SiO2 with fuchsite inclusions)
Mineral
Quartz Vein with Iron Staining
Silicon Dioxide (SiO2) with limonite/hematite staining
mineral
Sandstone (with Iron Staining)
Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)
sedimentary
Sandstone
Arenite (SiO2 based)
sedimentary
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions - SiO2)
mineral
Smoky Quartz
SiO2 (Silicon Dioxide)
mineral
Basalt (Gravel Pebble)
Basalt (contains pyroxene, plagioclase feldspar, and olivine)
igneous
Prehnite
Prehnite - Ca2Al(AlSi3O10)(OH)2
mineral
Chalcopyrite
Chalcopyrite (CuFeS2)
Mineral
Stiped Slate Beach Pebble
Low-grade Metamorphic Slate with Quartz Vein (SiO2 on Phyllosilicate base)
metamorphic
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Quartz Pebble (with probable Iron staining)
Silicon Dioxide (SiO2)
mineral