Amethyst Gemstone
Crystalline Quartz (SiO2 with iron impurities)
gemstone
Category
Synthetic (Not A Natural Rock)
Browse synthetic (not a natural rock) specimens identified by the Rock Identifier community.
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River Stone (Quartzite/Basalt)
Variable; often Quartzite (SiO2) or Basaltic rock
metamorphic
Limestone (specifically Travertine or Tufa)
Calcium Carbonate (CaCO3)
sedimentary
Sandstone (with Possible Iron Staining/Crust)
Arenite (SiO2 based)
sedimentary
Green Quartz (Prasiolite)
Silicon Dioxide (SiO2) with trace impurities
mineral
Sandstone
Arenite (typically SiO2 based)
sedimentary
Sandstone
Arenite (SiO2 primarily)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone
Arenite
sedimentary
Sandstone (lithic wake or graywacke)
Clastic sedimentary rock (primarily quartz and lithic fragments)
sedimentary
Vesicular Basalt (Scoria)
Mafic Igneous Volcanic Rock
igneous
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
River Pebble (Basalt or fine-grained Quartzite)
Fine-grained Mafic Rock (Volcanic Basalt)
igneous
Garnet (Almandine/Pyrope series)
Garnet Group - X3Y2(SiO4)3
mineral
Chalk
Calcium carbonate (CaCO3)
sedimentary
Chalk
Calcium Carbonate (CaCO3)
sedimentary
Orbicular granite (likely rapakivi-type granite)
Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
igneous
Mossy Rock
Mixed lithology rock with Bryophyta (moss)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone
Arenite
sedimentary
Quartz Pebble (Feldspathic / Chert Pebble)
Silicon Dioxide (SiO2) / Potassium Feldspar (KAlSi3O8)
sedimentary
Hag Stone
Perforated sedimentary rock (typically flint, chert, or limestone)
sedimentary
Sandstone
Sandstone (SiO2 dominated)
sedimentary
Sandstone
Arenite (SiO2 principal composition)
sedimentary
Sandstone
Arenite (SiO2 principal)
sedimentary
Black Tourmaline
Schorl (Na(Fe²⁺)₃Al₆(OH)₄(BO₃)₃Si₆O₁₈)
Mineral
Diamond (Rough)
Diamond (Carbon, C)
Mineral
Chert / Flint Nodule
Cryptocrystalline quartz (SiO2)
sedimentary
Brecciated Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Fossiliferous Limestone
Fossiliferous Limestone (CaCO3)
sedimentary
Borosilicate Glass (Manufactured)
SiO2 + B2O3 (Silicon dioxide and Boron trioxide)
Synthetic/Amorphous Solid
Amethyst Quartz
Amethyst (Silicon Dioxide, SiO2)
mineral
River Rock
Sedimentary Rock (various compositions)
sedimentary
Geode / Fossilized Gastropod or Shell Cast
Silicon dioxide (Quartz) replacement / fossil mold
sedimentary
Hag Stone (Chert/Flint with natural perforation)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Sandstone (Quartzose Sandstone)
Clastic sedimentary rock (SiO2 dominated)
sedimentary
Sandstone (with minor quartz and possible clay components)
Clastic Sedimentary Rock (SiO2 dominated)
sedimentary
Sandstone
Arenite (SiO2 principal)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary
Amethyst
Silicon Dioxide (SiO2) with iron impurities
mineral
Shale (possibly Carbonaceous or Oil Shale)
Argillaceous Sedimentary Rock
sedimentary
Sandstone
Sedimentary Rock (Quartz Sandstone)
sedimentary