Limonite (Iron Ore)
Limonite (Hydrated iron oxide - FeO(OH)·nH2O)
mineral
Category
Sedimentary (Secondary Mineral Formation)
Browse sedimentary (secondary mineral formation) specimens identified by the Rock Identifier community.
Jasper with Agate Inclusions
Silicon Dioxide (SiO2) - variety of Quartz/Chert
sedimentary
Chrysocolla in Matrix
Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Silicate/Secondary Copper Mineral)
mineral
Yellow Jasper
Silicon Dioxide (SiO2) with hydrated iron oxide impurities
sedimentary
Gneiss (Granitic Gneiss)
Gneiss (from German Gneis, related to 'spark')
metamorphic
Quartz
Quartz (SiO₂)
mineral
Satin Spar (commercially called Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Fluorite (Rainbow Fluorite)
Calcium Fluoride (CaF2)
mineral
Arkosic Sandstone (or Conglomeritic Sandstone fragment)
Arkose (rich in feldspar)
sedimentary
Pyrite
Pyrite (Iron Disulfide), FeS2
Mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Limestone (Brecciated/Recrystallized)
Calcium Carbonate (CaCO3)
sedimentary
Jasper
Jasper (Cryptocrystalline Quartz, SiO2)
sedimentary
Peridot
Olivine (Mg, Fe)2SiO4
mineral
Chert (Banded Variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Porous Quartzite
Metamorphosed Quartz-rich Sandstone (SiO2)
metamorphic
Spiny Oyster Shell
Spondylus (Calcium Carbonate, CaCO3)
mineral
Pearl
Calcium Carbonate (Aragonite) - CaCO3
mineral
Rhodonite
Manganese Silicate (Mn,Fe,Mg,Ca)SiO3
mineral
Chondrite Meteorite
Ordinary Chondrite (S-type Asteroid fragment)
mineral
Pyrite
Iron Disulfide (FeS2)
mineral
Chert Concretion (with typical hematite/limonite staining)
Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)
sedimentary
Turquoise and Hematite
Turquoise (CuAl6(PO4)4(OH)8·4H2O) and Hematite (Fe2O3)
mineral
Iron Ore / Ironstone Concretion
Mixture of iron oxide/hydroxide minerals, likely some combination of Hematite (Fe2O3), Goethite (α-FeOOH), and Limonite (a general term for hydrated iron oxides of variable composition) or potentially Bauxite (a mixture of aluminum hydroxides, often with iron oxides, (Al(OH)3) and FeO(OH)). The visual characteristics strongly suggest iron-rich material.
Mineral, specifically an iron ore
Chert (variant Flint/Jasper)
Microcrystalline Opaline Silica (SiO2)
sedimentary
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Carnelian
Chalcedony (Silicon Dioxide, SiO2 with Iron Oxide impurities)
mineral
Carnelian
Carnelian (variety of Chalcedony, SiO2)
mineral
Amethyst Geode
Silicon Dioxide with trace inclusions of Iron (SiO2)
mineral
Carnelian (a variety of Chalcedony)
Cryptocrystalline Quartz (SiO2) with iron oxide inclusions
Mineral
Hematite
Iron(III) oxide (Fe2O3)
mineral
Jasper
Chalcedony (cryptocrystalline quartz), SiO2
Sedimentary
Red Sandstone
Arenite (with Iron Oxide cement)
sedimentary
Conglomerate
Conglomerate (Detrital sedimentary rock)
sedimentary
Jasper
Silicon Dioxide (SiO2) with iron oxide impurities
sedimentary
Red Jasper
Silicon Dioxide (SiO2) with iron inclusions
sedimentary
Red Jasper
Jasper (Silicon Dioxide, SiO2)
sedimentary
Muscovite Mica
Muscovite (KAl₂(AlSi₃O₁₀)(F,OH)₂))
Mineral
Gold Nugget / Flake
Native Gold (Au)
mineral
Gold
Native Gold (Au)
mineral
Red Sandstone
Arenite (primarily Quartz with Iron Oxide)
sedimentary