Limonite (Ironstone) Concretion
FeO(OH)·nH2O (Hydrous ferric oxide)
sedimentary
Category
Man Made Object (Metal Alloy)
Browse man made object (metal alloy) specimens identified by the Rock Identifier community.
Learn about Man Made Object (Metal Alloy) in the encyclopedia
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Lava Rock (Scoria)
Scoria (Vesicular Basalt)
igneous
Fossil / Permineralized Bone
Tyrannosaurus rex fossil (Hydroxylapatite replaced by various minerals)
sedimentary
Vesicular Basalt
Vesicular Basalt
igneous
Desert Varnish (on Sandstone)
Rock Varnish (composed of Manganese oxides, Iron oxides, and Clay minerals)
sedimentary
Olivine (Peridot)
Magnesium Iron Silicate ((Mg, Fe)2SiO4)
Mineral
Green Fluorite
Fluorite (Calcium Fluoride - CaF2)
mineral
Amazonite
KAlSi3O8 (Potassium Feldspar, variety of Microcline)
Mineral
Basalt
Mafic Igneous Rock (composed primarily of Pyroxene and Plagioclase Feldspar)
igneous
Pyrite
Iron Sulfide (FeS2)
mineral
Serpentinite
Serpentinite (complex of lizardite, chrysotile, and antigorite: (Mg,Fe)3Si2O5(OH)4)
metamorphic
Serpentinite
Serpentinite (composed primarily of Serpentine minerals: Mg3Si2O5(OH)4)
metamorphic
Chert (Jasper/Flint variety)
Microcrystalline quartz (SiO2)
sedimentary
Mica Schist
Foliated Metamorphic Rock (Schist)
metamorphic
Pyrite
Iron Sulfide (FeS2)
mineral
Mica Schist
Mica Schist (Complex Silicate Rock)
metamorphic
Carnelian (red chalcedony), possibly red agate or jasper
Chalcedony, a microcrystalline variety of quartz; silicon dioxide (SiO₂), commonly colored red-orange by iron oxides. The specimen may include opaque jasper or agate zones.
gemstone
Rose Quartz (tumbled)
Rose Quartz (variety of Quartz, chemical formula SiO₂)
Mineral
Magnetite (Lodestone variety)
Magnetite (Iron(II,III) oxide, Fe3O4)
mineral
Bornite (Peacock Ore)
Bornite (Cu5FeS4)
mineral
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (often called Flint)
Chert (Cryptocrystalline Quartz, SiO2)
sedimentary
Fluorite
Calcium Fluoride (CaF2)
mineral
Red Swirl Beads (Likely Resin or Glass, simulating Red Jasper or Agate)
N/A (for the beads as pictured); Red Jasper: SiO2 (Chert variety); Red Agate: SiO2 (Chalcedony variety)
Organic (if resin) or Synthetic (if glass); simulating Sedimentary or Metamorphic (for natural stones)
Diamond (set in jewelry)
Diamond (Carbon, C)
mineral
Lepidolite
K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
mineral
Pink Lepidolite
Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)
mineral
Schist
Mica Schist (Quartz-Muscovite-Biotite Schist)
metamorphic
Quartz Vein in Host Rock
Crystalline Silicon Dioxide (SiO2) in Igneous/Metamorphic Matrix
mineral
Chert / Flint
Silicon Dioxide (SiO2)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Bauxite (Iron-stained Chert / Ironstone Aggregate)
Hydrous aluminum oxide mixture (mainly Gibbsite Al(OH)3, Boehmite γ-AlO(OH), and Goethite α-Fe3+O(OH))
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Hematitic Sandstone
Sandstone with Iron Oxide (Hematite) staining
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Fluorite
Calcium Fluoride (CaF2)
mineral
Gold
Native Gold (Au)
mineral
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Limonite and Goethite encrusted Chert/Ironstone
Hydrated Iron Oxide (FeO(OH)·nH2O) with cryptocrystalline Silica (SiO2)
sedimentary