Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)
mineral
Category
Mineral
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Limonite (Ironstone)
Hydrous ferric oxides (FeO(OH)·nH2O)
mineral
Weathered iron-rich rock, possibly oxidized basalt or laterite
Indeterminate; likely iron-oxide-bearing mafic rock (basaltic composition)
igneous
Malachite
Copper Carbonate Hydroxide, Cu2CO3(OH)2
mineral
Limonite Nodules / Goethite
Hydrated Iron Oxide-Hydroxide (FeO(OH)·nH2O / Fe2O3·nH2O)
mineral
Epidote in Matrix
Epidote; Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Arsenopyrite in Quartz Matrix
Arsenopyrite (FeAsS) with Quartz (SiO2)
mineral
Magnetite (Lodestone)
Magnetite (Fe3O4)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Sandstone Pebble
Arenite (Sandstone)
sedimentary
Sandstone
Arenite (SiO2 primarily)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrous ferric oxide)
mineral
Ironstone Concretion (Limonite/Goethite)
Ferruginous Sandstone or Limonite (FeO(OH)·nH2O)
sedimentary
Limonite/Goethite Nodule
Iron Oxyhydroxide (primarily FeO(OH)·nH2O)
mineral
Chalcopyrite
Copper Iron Sulfide (CuFeS2)
mineral
Polished orbicular granite (likely snowflake granite)
Granite, chiefly quartz, potassium feldspar, plagioclase, and dark biotite/amphibole minerals
igneous
Iron-stained Quartz
Silicon Dioxide (SiO2) with Iron Oxide (Limonite/Goethite) inclusions
mineral
Likely weathered quartz-rich rock, possibly granite or gneiss
Granite–gneiss assemblage; chiefly quartz, feldspar, and dark mica/amphibole
igneous
Tumbled jasper (likely picture/brecciated jasper)
Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides
mineral
Polished jasper carving or slab
Jasper, an opaque microcrystalline variety of quartz (SiO₂), likely iron-oxide-rich brecciated or orbicular jasper
gemstone
Green Aventurine and Clear Quartz Bracelet
Quartz variety with Fuchsite inclusions (Aventurine) and pure Silicon Dioxide (SiO2)
gemstone
Blue apatite (likely rough/tumbled specimen)
Apatite group, commonly fluorapatite — Ca5(PO4)3F
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Fluorite
Fluorite (Calcium Fluoride - CaF2)
mineral
Likely weathered quartz-rich rock fragment
Uncertain; possibly granitic pegmatite or quartz-bearing metamorphic rock
igneous
Fluorite
Calcium Fluoride (CaF2)
mineral
Rainbow Fluorite
Calcium Fluoride (CaF2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Vein Quartz in Basalt or Mafic Rock
Silicon Dioxide (Quartz veins in volcanic host rock)
igneous
Likely tumbled brown mineral fragment
Indeterminate; possibly iron-stained quartz, jasper, or carnelian
mineral
Chrysocolla
Hydrated copper phyllosilicate (Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Fossil Shark Tooth
Chondrichthyes (class)
fossil
Fossilized Shell Fragment
Bivalvia or Gastropoda (Class) fragment
fossil
Tumbled granite or granitic gneiss pebble
Granite/granitic gneiss, chiefly quartz, feldspar, and dark biotite or amphibole
igneous
Shark Tooth Fossil
Otodus obliquus (or similar prehistoric lamniform shark tooth)
fossil
Conglomeratic gravel / polymictic breccia
Polymictic rudite, likely anthropogenic or beach/stream gravel; composition varies
sedimentary
Apatite
Calcium phosphate fluoride/chloride, Ca5(PO4)3(F,Cl,OH)
mineral