Bog Iron / Limonite Concretion
Goethite/Limonite mixture (FeO(OH)·nH2O)
Category
Browse sedimentary (man made composite) specimens identified by the Rock Identifier community.
Bog Iron / Limonite Concretion
Goethite/Limonite mixture (FeO(OH)·nH2O)
Gastly (Trick or Trade Halloween Series)
Cellulose-carbonaceous composite (Lignocellulose laminated with pigmentary polymers)
Coquina
Biogenic Limestone (Calcium Carbonate, CaCO3)
Chert (Chert / Flint)
Microcrystalline Quartz (SiO2)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Limestone
Sedimentary Rock (Primarily CaCO3)
Polished black stone, likely black tourmaline or black obsidian
Most consistent with schorl tourmaline (NaFe3Al6(BO3)3Si6O18(OH)4), though black obsidian (volcanic glass) is also possible
Tumbled quartz-rich stone, possibly milky quartz or quartzite
Quartz (SiO₂), potentially quartzite if metamorphic
Banded Gneiss
Gneiss (Foliated Metamorphic Rock)
Chert (Flint)
Microcrystalline quartz (SiO2)
Chert
Microcrystalline Quartz (SiO2)
Chert (Flint)
SiO2 (Microcrystalline Quartz)
Riverstone (Sandstone Pebble)
Arenite (SiO2 with various lithic fragments)
Jasper
Silicon dioxide (SiO2) with impurities
Chert (often called Flint)
Chert (Microcrystalline or cryptocrystalline Silica, SiO2)
Coquina
Biogenic Limestone (CaCO3)
Coquina and Oyster Fossil Rock
Coquina limestone (Calcium Carbonate, CaCO3) containing fossilized Crassostrea / bivalve shells
Unakite
Altered granite (Epidote, Orthoclase Feldspar, and Quartz)
Quartz-rich gravel fragment
Quartz (silicon dioxide, SiO₂), possibly with feldspar or carbonate inclusions
Chert (varieties include Flint and Jasper)
Silicon Dioxide (SiO2)
Brecciated Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Banded Jasper / Chert Beach Pebble
Microcrystalline Quartz (SiO2)
Chert
Microcrystalline Quartz (SiO2)
Chert / Flint
Silicon Dioxide (Microcrystalline Quartz, SiO2)
Flint / Chert
Microcrystalline quartz (SiO2)
Chert (specifically Flint or Nodular Chert)
Silicon dioxide (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chalk
Carbonate rock (mainly CaCO3)
Chert (Jasper/Flint var.)
Silicon Dioxide (SiO2)
Chert (often called Flint or River Stone)
Microcrystalline alpha-quartz (SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
Natural freshwater pearls
Pearl (nacreous calcium carbonate; chiefly aragonite, CaCO₃)
Chert Arrowhead
Cryptocrystalline Quartz (SiO2)
Chert (specifically Flint)
Chert (SiO2)
Diamond in Kimberlite
Diamond (C in Kimberlite)
Chert (Flint)
Microcrystalline Quartz (SiO2)
Chert / Flint
Cryptocrystalline quartz (SiO2)
Chert (specifically Jasper or Flint)
Cryptocrystalline Quartz (SiO2)
Chert (Jasper variation)
Microcrystalline Quartz (SiO2)
Coquina
Bioclastic Limestone (Coquina)
Chalk
Calcium carbonate (CaCO3)