Biotite-rich gneiss or schist
Mica gneiss/schist; primarily quartz, feldspar, biotite, and possibly amphibole
metamorphic
Category
Igneous Or Metamorphic (Base Stone); Anthropogenic (Decoration)
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Venetian Gold Granite
Phaneritic Felsic Igneous Rock (Granite)
igneous
Blue Sapphire
Corundum (Al2O3)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Dark gray rock fragment, likely basalt
Basalt; chiefly plagioclase feldspar and pyroxene, commonly with minor olivine and magnetite
igneous
Granite
Granite (Phaneritic Igneous Rock)
igneous
Sodalite
Sodalite Na8(Al6Si6O24)Cl2
mineral
Likely basalt
Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine
igneous
Biotite Schist
Biotite Schist (K(Mg,Fe)3AlSi3O10(OH,F)2)
metamorphic
Black Tourmaline (Schorl)
Schorl (Sodium iron silicate hydroxide boron silicate); NaFe3Al6(BO3)3Si6O18(OH)4
mineral
Granite Pebble
Granite (Phaneritic intrusive igneous rock)
igneous
Likely black cabochon gemstone pendant
Uncertain; possibly black star sapphire, black spinel, or obsidian
gemstone
Porphyry
Porphyritic Basaltic Andesite
igneous
Quartz Vein in Gneiss or Schist
Metamorphic rock with SiO2 vein
metamorphic
Ruby / Pink Sapphire
Corundum (Al2O3 with Chromium impurities)
gemstone
Likely biotite-bearing metamorphic rock (schist or gneiss)
Mica schist/gneiss; chiefly quartz, feldspar, and biotite mica
metamorphic
Yellow Quartzite (River Cobble)
Quartzite (SiO2)
metamorphic
Dark basalt or vesicular volcanic rock
Basalt; predominantly plagioclase, pyroxene, and commonly olivine, with possible iron-oxide alteration
igneous
Chert (Arrowhead Fragment)
Microcrystalline Quartz (SiO2)
sedimentary
Geode with Iron-Stained Quartz/Calcite
Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) in Sedimentary Matrix
sedimentary
Quartzite
Metamorphic Quartzite (SiO2)
metamorphic
Granitoid (Granite/Gneiss)
Granitoid silicate rock, primarily quartz and feldspar
igneous/metamorphic
Vesicular Basalt
Basalt (Mafic Extrusive Igneous Rock)
igneous
Gneiss
Gneiss
metamorphic
Epidote
Epidote; Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
mineral
Citrine Quartz
Silicon Dioxide (SiO2)
mineral
Muscovite
KAl2(AlSi3O10)(OH)2
mineral
Obsidian Arrowhead
Volcanic Glass (Primary composition: SiO2)
igneous
Muscovite Mica
Muscovite - KAl2(AlSi3O10)(F,OH)2
mineral
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
mineral
Muscovite Mica
Muscovite (KAl2(AlSi3O10)(OH)2)
mineral
Epidote-bearing Rock / Epidote Inclusion
Epidote (Ca2(Al, Fe)3(SiO4)3(OH)) in host rock
mineral
Weathered quartz-bearing rock, possibly iron-stained quartzite or granitic pegmatite
Indeterminate; likely quartz-rich silicate rock with iron-oxide staining (SiO₂-dominant)
igneous
Slag (Industrial Glass Slag)
Amorphous Silica / Ferro-silicate Slag
mineraloid / anthropogenic
Granitic Gneiss
Gneiss (Polymetamorphic Granitic Gneiss)
metamorphic
River Stone (Basalt Porphyry)
Porphyritic Basalt
igneous
Basalt (Polished)
Extrusive mafic igneous rock
igneous
Probable weathered sulfide-bearing rock
Indeterminate; possibly pyrite- or chalcopyrite-bearing matrix
mineral
Schist
Crystalline Metamorphic Rock (Schistose)
metamorphic
Muscovite (Mica)
Muscovite - KAl2(AlSi3O10)(OH)2
Mineral
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Chert (specifically Flint Arrowhead)
Silicon dioxide (SiO2) - Microcrystalline Quartz
sedimentary