Blue calcite (likely)
Calcite, CaCO₃
mineral
Category
Mineral Specimen
Browse mineral specimen specimens identified by the Rock Identifier community.
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Blue Apatite
Fluorapatite / Apatite Group Ca5(PO4)3(F,Cl,OH)
mineral
Likely iron-rich slag or weathered ironstone
Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag
mineral
Yellow Quartz (Citrine Quartz Pebble)
Silicon Dioxide (SiO2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Quartz Druzy on Agate (River Cobble)
Silicon Dioxide (SiO2)
Mineral / Sedimentary (often associated with volcanic hosts)
White quartz pebble
Quartz (silicon dioxide, SiO₂), likely milky quartz
mineral
Quartz (Milky/Smoky mix)
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
mineral
Moqui Marble
Ironstone Concretion (Goethite/Hematite shell with Sandstone core)
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Erythrite
Erythrite (Cobalt Bloom) - Co3(AsO4)2·8H2O
mineral
Likely weathered quartz-rich stone
Indeterminate; possibly quartz-bearing granite or milky quartz
mineral
Chrysocolla
(Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Olivine in Basalt matrix
Olivine (Magnesium Iron Silicate - (Mg, Fe)2SiO4)
igneous
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Garnet (specifically Almandine)
Almandine (Fe3Al2(SiO4)3)
mineral
Yellow Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
sedimentary
Blue Apatite
Fluorapatite / Chlorapatite / Hydroxylapatite (Ca5(PO4)3(F,Cl,OH))
mineral
Limonite / Goethite pseudomorph
Hydrated Iron Oxide (FeO(OH)·nH2O)
mineral
Lepidolite Pebble
K(Li,Al)3(Al,Si,3O10)(F,OH)2
mineral
Chalcedony in Matrix
Silicon Dioxide (SiO2)
mineral
Amethyst (Chevron or Banded variety)
Silicon Dioxide (SiO2) with iron impurities
mineral
Likely dark green-gray metamorphic pebble
Indeterminate; possibly chlorite schist, serpentinite, or amphibolite
metamorphic
Pink Sapphire (Corundum)
Aluminum Oxide (Al2O3) with Chromium/Iron impurities
gemstone
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Epidote
Epidote (Ca2(Al, Fe)3(SiO4)3(OH))
mineral
Vanadinite
Vanadinite (Pb5(VO4)3Cl)
mineral
Pegmatitic Granite
Granite (composed of Quartz, Feldspar, and Mica)
igneous
Limonite Concretion
Limonite (Hydrated iron oxide) FeO(OH)·nH2O
sedimentary
Pyrite (Limonite Pseudo-morph after Pyrite)
Iron sulfide (FeS2) transitioning to Iron oxide-hydroxide (FeO(OH)·nH2O)
mineral
Pyrite in Quartzite/Graphite Matrix
Iron Sulfide (FeS2)
Mineral
Hemimorphite on Limonite Gossan
Hemimorphite (Zn4Si2O7(OH)2·H2O) on Limonite matrix
mineral
Kidney Stone (Calcium Oxalate / Uric Acid)
Calcium Oxalate Monohydrate (Whewellite) / Calcium Oxalate Dihydrate (Weddellite)
mineral
Likely smoky quartz-bearing rock or quartz crystal
Quartz, silicon dioxide (SiO₂), possibly smoky quartz with iron- or irradiation-related coloration
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Cobaltian Calcite (Cobaltoan Calcite)
Cobalt-bearing Calcite (Ca,Co)CO3
mineral
Prase Quartz on Feldspar
Quartz (Silicon Dioxide, SiO2) with Hedenbergite inclusions on Potassium Feldspar (KAlSi3O8)
mineral
Sunstone
Oligoclase (Plagioclase Feldspar) / (Ca,Na)(Al,Si)4O8
mineral
Ferruginous Quartz
Silicon Dioxide (SiO2) with Iron Oxide inclusions
Mineral
Prehnite
Ca2Al(AlSi3O10)(OH)2 (Calcium Aluminum Silicate hydroxide)
mineral