Marble
Recrystallized Calcite (CaCO3)
metamorphic
Category
Mineraloid (Human Made Geological Specimen)
Browse mineraloid (human made geological specimen) specimens identified by the Rock Identifier community.
Sandstone
Arenite (SiO2 based typically)
sedimentary
Chert (Commonly known as Flint)
Silicon Dioxide (SiO2)
sedimentary
Pyrite
Iron Sulfide (FeS2)
mineral
Ferruginous Sandstone Concretion (Ironstone Phosphorite)
Ferruginous Sandstone (variable Fe-oxide/hydroxide composition)
sedimentary
Calcite
Calcite (calcium carbonate, CaCO₃)
mineral
Chert (Jasper)
Cryptocrystalline Quartz (SiO2)
sedimentary
Diamond
Pure Carbon (C)
mineral
Sandstone (River Pebble)
Clastic Sedimentary Rock (primarily Quartz)
sedimentary
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Glacial Erratic (Sandstone/Quartzite)
Glacial Erratic specimen (likely Orthoquartzite or Feldspathic Sandstone)
sedimentary or metamorphic
Asphalt (Bituminous Pavement Bit)
Bitumen-bound aggregate (Petrochemical-bound composite)
sedimentary (anthropogenic/technogenic)
Green Aventurine
Aventurine Quartz (SiO2 with Fuchsite inclusions)
mineral
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Red Jasper
Silicon Dioxide (Microcrystalline Quartz), SiO2
sedimentary
River Stone (Chert/Siltstone)
Cryptocrystalline Quartz (SiO2) with trace impurities
sedimentary
Tumbled yellow quartz (likely citrine or iron-stained quartz)
Quartz, SiO₂; yellow color from trace iron or irradiation/heat-related coloration
mineral
Chert (or Limestone)
Sedimentary Cryptocrystalline Quartz (SiO2) or Calcium Carbonate (CaCO3)
sedimentary
Chert (Jasper/Agate variety)
Cryptocrystalline Quartz (SiO2)
sedimentary
Graphite
Graphite (Carbon, C)
mineral
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Clear Quartz Crystal
Silicon Dioxide (SiO2)
mineral
Chert / Flint
Silicon Dioxide (Microcrystalline Quartz, SiO2)
sedimentary
Rounded weathered rock, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; precise identification requires testing
igneous
Rounded quartz-rich beach pebble
Likely milky quartz or quartzite (SiO₂)
mineral
Amazonite
Amazonite (KAlSi3O8, a variety of Microcline)
mineral
Blue Chalcedony (Blue Lace Agate variety)
Silicon Dioxide (SiO₂)
mineral
Polished/tumbled quartz-rich pebble, possibly jasper or quartzite
Indeterminate; likely microcrystalline quartz (SiO₂), potentially iron-stained jasper or quartzite
metamorphic
Chert (varieties: Flint or Jasper)
Silicon dioxide (SiO2) / Microcrystalline Quartz
sedimentary
Rough Diamond
Diamond (pure Carbon, C)
mineral
Rounded quartz-rich pebble
Likely quartzite or quartz-rich sandstone pebble; SiO₂-dominant
sedimentary
Pyrite
Iron Sulfide (FeS2)
mineral
Amber
Succinite
Organic Mineraloid
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Asphalt (Bituminous Concrete)
Composite material (bitumen binder with mineral aggregate)
man-made rock (technosol)
Granite
Phaneritic Igneous Rock (primarily SiO2, Al2O3, K2O, Na2O)
igneous
Basalt with Garnet inclusions
Basalt containing Nesosilicate (Garnet Group, likely Almandine Fe3Al2Si3O12)
igneous
Chert (Flint Pebble)
Silicon Dioxide (SiO2)
sedimentary
Weathered gray rock, likely basaltic or andesitic fragment
Fine-grained mafic to intermediate volcanic rock; exact identification requires fresh surface and testing
igneous
Iron-stained quartz-bearing rock
Quartz (SiO₂), likely in a limonite/goethite-rich matrix
mineral
Milky quartz
Quartz, silicon dioxide (SiO₂)
mineral
Milky Quartz with Iron Staining
Quartz (Silicon Dioxide, SiO2)
mineral