Serpentine pendant
Serpentinite; chiefly antigorite, lizardite, or chrysotile Mg₃Si₂O₅(OH)₄
metamorphic
Category
Synthetic Material (Not A Rock Or Mineral)
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Breccia Pebble
Sedimentary Breccia
sedimentary
Quartz (Small Fragment)
Silicon Dioxide (SiO2)
mineral
Sandstone (Quartzose Sandstone)
Arenite (SiO2)
sedimentary
Tumbled carnelian (likely chalcedony)
Carnelian, orange-red cryptocrystalline quartz (SiO₂), a variety of chalcedony
gemstone
Chert (Yellow Jasper / Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Quartz geode (likely amethyst-bearing)
Silica geode; quartz, SiO₂, with possible amethyst and minor iron oxides
mineral
Olivine in Basalt (Peridot)
Magnesium Iron Silicate (Mg,Fe)2SiO4 (Mineral) / Scoriaceous Basalt (Host Rock)
igneous
Sandstone (Quartz Arenite)
Sandstone (SiO2 with possible mineral cements)
sedimentary
Sandstone
Clastic sedimentary rock (quartz arenite)
sedimentary
Tumbled purple agate (likely grape agate or amethystine chalcedony)
Microcrystalline quartz, SiO₂; purple coloration commonly from iron, manganese, or inclusions
mineral
Cubic Zirconia (Jewelry Setting)
Cubic Zirconia (ZrO2)
gemstone
Caliche (with Lichen Cover)
Calcium carbonate-cemented soil layer (CaCO3)
sedimentary
Sandstone
Arenite
sedimentary
Sandstone
Arenite (SiO2 based with various mineral cements)
sedimentary
Unakite
Unakite; epidote–pink feldspar–quartz rock
metamorphic
Porphyry
Porphyritic Andesite / Basaltic Porphyry
igneous
Sandstone
Arenite (primarily SiO2)
sedimentary
Red Sandstone
Arenite (composed primarily of Quartz and Iron Oxide)
sedimentary
Red Granite
Intrusive Igneous Rock (Felsic)
igneous
Diamond (or Diamond Simulant)
Carbon (C) or Cubic Zirconia (ZrO2)
gemstone
Sandstone
Arenite (SiO2 principal component)
sedimentary
River Stone (Quartzite/Siltstone mixture)
Silicon Dioxide (SiO2) based metamorphosed sandstone
metamorphic or sedimentary
Polished green aventurine (likely)
Quartzite dominated by quartz (SiO₂), commonly containing fuchsite mica
mineral
Rounded granite or granitic gneiss cobble
Granite, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
igneous
Garnet Schist
Garnetiferous Mica Schist
metamorphic
River Cobble (Quartzite or Sandstone)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Scoria (Volcanic Rock)
Scoria (often basaltic scoria)
Igneous
Graphic Granite
Pegmatitic Granite (Quartz and Microcline K-Feldspar mixture)
igneous
Red Sandstone
Arenite (Ferruginous Sandstone)
sedimentary
Sandstone
Arenite (primarily Quartz Arenite)
sedimentary
Turquoise
Turquoise (CuAl6(PO4)4(OH)8·4H2O)
mineral
Sandstone (Ferruginous)
Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)
sedimentary
Sedimentary Breccia
Clastic Breccia (CaCO3/SiO2 matrix)
sedimentary
Sandstone (Banded)
Clastic Sedimentary Rock (primarily Quartz, SiO2)
sedimentary
Tufa Rock and Tumbled Gemstones
Calcareous Tufa (Calcium Carbonate, CaCO3)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Chlorastrolite (Greenstone)
Chlorastrolite (variety of Pumpellyite) - Ca2(Mg,Fe)Al2(SiO4)(Si2O7)(OH)2 · H2O
mineral
Granite
Felsic intrusive igneous rock
igneous
Sandstone (specifically Arkose or Ferruginous Sandstone)
Sandstone (SiO2 predominant)
sedimentary
Gravel and Pavement Aggregates
Unconsolidated rock fragments / detrital sediments
sedimentary