Limonite (Iron Ore Congcretion)
Limonite (a mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)
mineral
Category
Man Made Material (Metal)
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Porphyritic rhyolite (likely lithophysal/vesicular rhyolite)
Rhyolite; chiefly quartz and alkali feldspar, with minor plagioclase and iron-bearing minerals
igneous
Gold-bearing sulfide ore, likely gossan or quartz-vein material
Native gold (Au) with probable iron oxides/hydroxides and sulfides, possibly quartz matrix
mineral
Blue chalcedony (likely dyed or polished)
Chalcedony, microcrystalline quartz (SiO₂)
mineral
Weathered, porous limestone (probable fossiliferous limestone)
Calcite-rich limestone; predominantly CaCO₃
sedimentary
Polished orbicular granite
Granite, chiefly quartz, alkali feldspar, plagioclase, and biotite/amphibole
igneous
Pegmatite with quartz, feldspar, mica, and tourmaline
Granitic pegmatite; chiefly quartz (SiO₂), feldspar, muscovite, and black schorl tourmaline (NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)
igneous
Quartz-rich metamorphic rock (likely mica schist or gneiss)
Quartz–feldspar–mica assemblage; probable biotite schist/gneiss
metamorphic
Chalcedony (gray-white agate)
Microcrystalline quartz, SiO₂
mineral
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (and Flint)
Silicon Dioxide (SiO2)
sedimentary
Chert (Flint)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Carved Gemstone Mushroom
Quartz / Feldspar composite (Carved lapidary art)
gemstone
Fossilized Coral
Rugose coral / Tabulate coral fossil in limestone matrix
fossil
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Iron sulfide-rich ore, possibly pyrite-bearing gossan
Likely pyrite (FeS₂) with iron oxides/hydroxides and host rock; exact identification requires testing
mineral
Crushed Stone (Gravel/Aggregates)
Crushed rock aggregate (varied composition including Granite, Limestone, and Quartz)
sedimentary and igneous (mixed)
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Tumbled chalcedony (likely milky quartz)
Chalcedony, cryptocrystalline SiO₂; possibly quartz-rich chert
mineral
Schist
Schist
metamorphic
Tumbled brown jasper
Microcrystalline quartz/chalcedony (SiO₂), commonly iron-oxide stained
sedimentary
Granite River Cobble
Phaneritic Felsic Igneous Rock (Granite)
igneous
Quartzite
Quartzite (principally SiO2)
metamorphic
Yellow Quartzite Pebble
Quartzite (SiO2)
metamorphic
Plume Agate or Moss Agate
Agate (SiO2)
mineral
Sandstone
Arenite (SiO2 primarily)
sedimentary
Dalmatian Stone and Lapis Lazuli
Dalmatian Stone (peralkaline rock) with Lapis Lazuli (metamorphic rock)
igneous
Polished chalcedony (likely jasper or agate)
Microcrystalline quartz, SiO₂; chalcedony with iron-oxide inclusions
mineral
Small vesicular volcanic rock, likely scoria
Scoria; predominantly basaltic to andesitic volcanic rock
igneous
Likely tumbled jasper or iron-rich chert
Microcrystalline quartz (SiO₂), potentially hematite/goethite-bearing
mineral
Quartz Crystal
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Kyanite
Al2SiO5
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz pebble
Silicon dioxide (SiO2)
mineral
Quartz
Silicon Dioxide (SiO2)
mineral
Quartz
Silicon dioxide (SiO2)
Mineral
Quartz, Sandstone, and Siltstone specimens
Silicon Dioxide (SiO2) and Clastic Sedimentary Rocks
mineral and sedimentary
Rounded brown-gray stone, possibly weathered conglomerate or sandstone
Indeterminate clastic sedimentary rock; likely poorly cemented sandstone/conglomerate
sedimentary
Granite
Intrusive igneous rock composed mainly of quartz, alkali feldspar, and plagioclase
igneous