Limonite (Bog Iron)
Limonite (Hydrated iron(III) oxide-hydroxide) - FeO(OH)·nH2O
mineral
Category
Mineral Based Alloy (Anthropogenic)
Browse mineral based alloy (anthropogenic) specimens identified by the Rock Identifier community.
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Chalcedony (Agate/Jasper mix)
Cryptocrystalline Sillimanite (Quartz) - SiO2
mineral
Asphalt / Road Aggregate
Bituminous Conglomerate (synthetic)
sedimentary
Milky Quartz with Iron Staining
Silicon Dioxide (SiO2)
mineral
Green Kyanite
Kyanite (Al2SiO5)
mineral
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)
mineral
Granite
Phaneritic plutonic rock (Quartz, Feldspar, Mica)
igneous
Fossilized Crab Carapace (Concretion)
Decapoda (fossil), typically preserved in calcite or siderite concretion
sedimentary
Granite Glacial Erratic
Intrusive Phaneritic Felsic Rock (Granite)
igneous
Sandstone
Sedimentary Rock (Quartz arenite / Lithic sandstone)
sedimentary
Anthracite Coal
Anthracite (Carbon-based solid)
metamorphic
Native Gold Nugget
Native Gold (Au)
mineral
Sandstone (Pebble)
Arenite
sedimentary
Celestite (Celestine)
Strontium Sulfate (SrSO4)
mineral
Celestite (Celestine)
Strontium Sulfate (SrSO4)
mineral
Labradorite
Labradorite ((Ca, Na)(Al, Si)4O8)
mineral
Tumbled chalcedony or quartz-rich stone
Microcrystalline quartz, SiO₂; possibly pale chert or chalcedony
mineral
Desert Rose
Selenite Rose (Gypsum: CaSO4·2H2O)
mineral
River Cobble (Quartzite or Gneiss)
Metamorphic crystalline rock (predominantly SiO2 based)
metamorphic
Sandstone River Pebble
Arenite (SiO2 predominantly)
sedimentary
Native copper-bearing rock
Native copper (Cu), likely with copper oxides/carbonates in a host rock
mineral
Native bismuth
Bismuth (Bi), commonly forming hopper crystals or aggregates
mineral
Native copper nugget
Copper (Cu), commonly with cuprite and copper-oxide alteration
mineral
Sandstone (Water-worn Cobble)
Arenite (SiO2 with CaCO3 or Fe2O3 cement)
sedimentary
Tumbled Carnelian and Quartz Mix
Silicon Dioxide (SiO2) with iron oxide impurities
mineral
Diamond
Native Carbon (C)
mineral
Gold Nugget
Native Gold (Au)
mineral
Gold Nugget
Native Gold (Au)
mineral
Silver (Jewelry Specimen)
Native Silver (Chemical Formula: Ag)
mineral
Likely chlorite-bearing schist (possibly greenschist)
Chlorite–quartz–mica schist; commonly contains muscovite/biotite and feldspar
metamorphic
Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')
Calcite (Calcium Carbonate, CaCO3)
sedimentary
Sandstone
Arenite
sedimentary
Turquoise in Matrix
Hydrated copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O
mineral
Tree Agate (or Moss Agate), faceted into a crystal tower
Dendritic Agate (Silicon Dioxide, SiO2)
Mineral
Sandstone (with Limonite/Iron Staining)
Arenite (SiO2 based) with FeO(OH) staining
sedimentary
Sandstone (with Moss/Lichen Growth)
Sandstone (Quartz Arenite / Lithic Arenite)
sedimentary
Concrete Fragment
Hardened Portland cement and mineral aggregate
sedimentary (anthropogenic)
Sandstone
Arenite (primarily SiO2)
sedimentary
Chrysocolla
Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4 nH2O
mineral
Fossilized Brachiopod
Brachiopoda (e.g., Rhynchonellida or Spiriferida)
sedimentary
Fired Clay Brick (Anthropic Rock substitute)
Anthropogenic polycrystalline ceramic (predominantly Mullite and Quartz: Al6Si2O13 + SiO2)
metamorphic (man-made / anthropic)
Tumbled blue glassy mineral, possibly sodalite or blue aventurine
Identification uncertain; likely sodalite (Na₈Al₆Si₆O₂₄Cl₂) or blue-dyed quartz/slag-like material
mineral