Ferruginous Siltstone
Siltstone with Magnetite/Hematite bands
sedimentary
Category
Not A Natural Rock (Man Made Composite)
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Limestone
Calcium Carbonate (CaCO3)
sedimentary
Sandstone
Arenite
sedimentary
Pink Granite
Phaneritic Felsic Igneous Rock (high K-feldspar)
igneous
Glauconitic Sandstone
Glauconitic Sandstone with high Glauconite concentration ((K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)
sedimentary
River Rock (Basalt or Siltstone)
Basalt (Aphanitic Igneous Rock)
igneous
Sandstone (with Iron concretions/staining)
Arenite (composed primarily of Quartz and Feldspar with Iron Oxide cement)
sedimentary
Quartzite River Rock
Quartzite (primarily SiO2)
metamorphic
Mother of Pearl (Nacre)
Calcium Carbonate (primarily aragonite, with conchiolin)
Organic Gemstone/Biomineral
Quartzite
Quartzite (SiO2)
metamorphic
Moldavite
Tektite (Natural Silicate Glass)
gemstone
Amethyst
Amethyst (Silica mineral, SiO2)
mineral
Tumbled citrine or iron-stained quartz
Quartz (SiO₂), likely iron-oxide-stained or natural citrine
mineral
Fossilized tooth or tooth fragment
Indeterminate vertebrate tooth; likely mammalian, mineralized hydroxyapatite
fossil
Precious Coral (Red Coral)
Corallium rubrum (Calcium Carbonate, CaCO3)
mineral
River Cobble (Sandstone / Greywacke)
Sedimentary Rock (predominantly Quartz, Feldspar, Lithic fragments)
sedimentary
Conglomerate
Clast-supported polymict conglomerate
sedimentary
Sandstone (River Cobble)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Pink Granite
Granite (Phaneritic Felsic Igneous Rock)
igneous
Granite
Phaneritic plutonic felsic igneous rock
igneous
Banded Gneiss River Pebble
Gneiss
metamorphic
Amethyst
Crystalline Quartz (SiO2 with iron impurities)
gemstone
Dyed Blue Agate
Silicon Dioxide (SiO2) with artificial pigment
mineral
Pickled Dragon Eggs (Fictional Interpretation: Purple Agate or Amethyst Geodes)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
mineral
Sandstone (Ferruginous)
Clastic Sedimentary Rock (SiO2 with Fe2O3)
sedimentary
Raw gold nugget or gold-bearing quartz
Native gold (Au), possibly with quartz (SiO₂) and iron-oxide staining
mineral
Pink Dyed Agate
Silicon Dioxide (SiO2) - Variety Agate
mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Shale (with Iron Oxide staining)
Fissile Mudstone (primarily Quartz and Clay minerals)
sedimentary
Gneiss
Gneiss (foliated metamorphic rock)
metamorphic
Basalt
Basalt
igneous
Tumbled dark gray stone, likely basalt
Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine
igneous
Yellow Quartz (Citrine/Yellow Jasper mix)
Silicon Dioxide (SiO2)
mineral
Granite
Phaneritic intrusive igneous rock
igneous
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Tufa Rock and Tumbled Gemstones
Calcareous Tufa (Calcium Carbonate, CaCO3)
sedimentary
Pink Granite
Phaneritic Felsic Igneous Rock (Granite)
igneous
Basalt Arrowhead (worked stone)
Aphanitic mafic volcanic rock (Basalt)
igneous
Tumbled porphyritic granite
Granite, primarily quartz, alkali feldspar, plagioclase, and biotite/hornblende
igneous
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral