Tumbled citrine (possibly heat-treated amethyst)
Quartz, SiO₂; trigonal crystal system
gemstone
Category
Mineral
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Amethyst (polished bead)
Quartz, SiO₂; purple variety colored mainly by iron-related defects
gemstone
Amethyst cluster
Amethyst, purple variety of quartz (SiO₂); trigonal crystal system
mineral
Tumbled amethyst
Quartz, SiO₂; purple color typically from trace iron and natural irradiation
gemstone
Purple druzy quartz (likely dyed or coated)
Quartz, SiO₂ (trigonal crystal system)
mineral
Tumbled amethyst
Quartz, SiO₂; purple coloration from trace iron and natural irradiation
mineral
Amethyst (likely tumbled or polished)
Quartz, SiO₂; purple color commonly caused by trace iron and natural irradiation
mineral
Yellow Quartz
Silicon Dioxide (SiO2)
mineral
Rock Specimen
Unclassified rock specimen
sedimentary
Polished orbicular jasper (likely ocean jasper)
Silica-rich microcrystalline quartz/chalcedony with iron oxides and accessory minerals; SiO₂-dominant
mineral
Quartz-rich gneiss (probable banded metamorphic rock)
Gneiss; composition chiefly quartz, feldspar, and mica, possibly with amphibole
metamorphic
Blue Apatite
Calcium phosphate mineral, Ca5(PO4)3(F,Cl,OH)
mineral
Fossilized bone fragment, possibly vertebra
Fossil bone (mineralized hydroxyapatite; exact taxon indeterminate)
fossil
Picture Jasper
Silicon Dioxide (SiO2) with iron oxide and silicate minerals
sedimentary
River Stones (Quartzite and Sandstone)
Quartzite / Sedimentary Rock (SiO2 dominant)
sedimentary
Milky quartz fragment
Quartz, silicon dioxide (SiO₂)
mineral
Blue Apatite
Apatite (Ca5(PO4)3(F,Cl,OH))
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Fluorite
Calcium fluoride (CaF2)
mineral
Malachite and Azurite on Gossan (Ironstone Matrix)
Cu2CO3(OH)2 (Malachite) on FeO(OH)·nH2O (Limonite/Gossan)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Weathered vesicular volcanic rock (likely basalt or andesite)
Amygdaloidal basalt/andesite; cavities may contain calcite, zeolites, or silica minerals
igneous
Weathered granitic gneiss
Quartz–feldspar–biotite gneiss (likely granitic gneiss)
metamorphic
Granite (small weathered fragment)
Granite, composed chiefly of quartz, feldspar, and mica
igneous
Weathered granite pebble
Granite, composed chiefly of quartz, feldspar, and mica
igneous
Granite (likely a granitic rock)
Granite, composed chiefly of quartz, feldspar, and dark mica or amphibole
igneous
Likely amphibolite
Amphibolite, composed mainly of hornblende (amphibole) and plagioclase feldspar
metamorphic
Green-speckled igneous rock, likely epidote-bearing basalt or serpentinite
Tentatively epidote-bearing basalt (compositionally uncertain from the image)
igneous
Shark Tooth Fossil
Carcharocles megalodon or similar extinct shark tooth
fossil
Sandstone
Clastic Sedimentary Rock
sedimentary
Note regarding baguette production (not a rock)
Digital text image - Somali language
not a rock
Tumbled green stone, likely serpentine
Serpentine-group minerals, commonly antigorite or lizardite; approximate formula Mg₃Si₂O₅(OH)₄
mineral
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Yellow Topaz
Aluminum silicate fluoride hydroxide, Al2SiO4(F,OH)2
gemstone
Likely porphyritic volcanic rock
Indeterminate; possibly porphyritic andesite or basalt
igneous
Quartz-veined rock
Silicate rock with quartz vein (SiO2)
igneous
Milky quartz
Quartz (SiO₂)
mineral
Likely biotite-rich schist
Mica schist, likely containing biotite and quartz; exact identification requires examination
metamorphic
Topaz
Al2SiO4(F,OH)2
mineral