Calcite specimen
Calcite (calcium carbonate, CaCO₃), likely botryoidal or drusy calcite
mineral
Category
Mineraloid (Human Made Geological Specimen)
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Quartz Geode Fragment
Silicon Dioxide (SiO2)
mineral
Fossil Coral
Scleractinia (fossilized calcium carbonate)
sedimentary
Chert (Cherty Flint/Jasper variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
sedimentary
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Colorless faceted gemstone (most likely synthetic cubic zirconia)
Cubic zirconia, ZrO₂ (likely synthetic); natural alternatives include quartz or diamond
gemstone
Calcite
Calcium Carbonate (CaCO3)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Agate (or Chalcedony)
Silicon Dioxide (SiO2)
mineral
Gold Ore in Matrix
Native Gold (Au) in Quartz/Host Rock
mineral
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Organic Materia (Not a rock or mineral)
Unidentified weathered rock, possibly quartz-bearing granite or rhyolite
Indeterminate; likely quartz–feldspar-rich silicate rock
igneous
Coarse-grained Quartz with Feldspar inclusions
Crystalline Quartz (SiO2) with Orthoclase/Plagioclase Feldspar inclusions
igneous
Unidentifiable Specimen
Undetermined
Unknown
Quartz pebble / Quartzite
Silicon Dioxide (SiO2)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartzite Pebble
Metamorphic Quartz (SiO2)
metamorphic
Granite Pebble
Felsic Intrusive Igneous Rock (composed of Quartz, Feldspar, and Mica)
igneous
Yellow Quartzite (River Pebble)
Silicon Dioxide (SiO2) with iron oxide inclusions
metamorphic
Carnelian
Carnelian (Cryptocrystalline Quartz, SiO2)
mineral
Quartz (likely Jasper or Chert variety)
Quartz (SiO₂)
Mineral
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Chert Nodule
Microcrystalline Silica (SiO2)
sedimentary
Serpentinite
Serpentinite (composed primarily of serpentine-group minerals like antigorite, chrysotile, and lizardite; chemical formula varies but generally Mg3Si2O5(OH)4)
Metamorphic Rock
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Raw Quartz
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Pyrite-bearing quartz vein rock
Pyrite (FeS₂) in quartz, possibly with iron-oxide weathering products
mineral
Flint / Chert
Microcrystalline Quartz (SiO2)
sedimentary
Flint with Fossil Inclusion
Cryptocrystalline quartz (SiO2) enclosing fossilized organic remains
sedimentary
Banded Iron Formation (BIF)
Banded Iron Formation (predominantly Hematite and Chert)
sedimentary
Basalt with Granite Inclusions (Xenolith)
Mafic Igneous Rock (Basalt) with Felsic Igneous Inclusion (Granite)
igneous
Sandstone with Hematite staining
Arenite with Fe2O3 inclusions
sedimentary
Septarian Nodule
Septarian Concretion (CaCO3 with Siderite/Calcite/Aragonite)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO₂ / Silicon Dioxide)
mineral
Schorl (Black Tourmaline)
Schorl (Sodium Iron Aluminum Borosilicate Hydroxide), NaFe3Al6(BO3)3Si6O18(OH)4
mineral
Ironstone Concretion / Limonite Node
Goethite and Limonite (FeO(OH) nH2O)
sedimentary
Mookaite Jasper
Radiolarite (Silicified radiolarian chert), SiO2
sedimentary
Vesicular Basalt with Amygdules
Amygdaloidal Basalt
igneous
Graphic Granite
Graphic Granite (Granitic Pegmatite), typically KAlSi3O8 (Feldspar) + SiO2 (Quartz)
igneous
Sandstone (Ferruginous)
Arenite (composed primarily of SiO2 with Fe2O3 cement)
sedimentary