Limestone Concretion (Botryoidal/Calcareous Nodules)
Calcium Carbonate Concretion (CaCO3)
Category
Browse organic gemstone (not a rock) specimens identified by the Rock Identifier community.
Limestone Concretion (Botryoidal/Calcareous Nodules)
Calcium Carbonate Concretion (CaCO3)
Shungite
Shungite (carbon-rich Precambrian rock)
Limestone with Quartz/Calcite Veins
Sedimentary Limestone (CaCO3 with SiO2 or CaCO3 intrusions)
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Serpentine
Serpentinite (a rock composed primarily of serpentine minerals like antigorite, chrysotile, and lizardite; general formula (Mg, Fe)3Si2O5(OH)4)
Weathered River Rock (likely Chert or Basalt with algae)
Silicon dioxide (SiO2) with organic biofilm
Quartz
Silicon Dioxide (SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert Pebble
Chert (Microcrystalline Quartz, SiO2)
Moss Agate
Chalcedony (Silicon Dioxide, SiO2) with inclusions
Jasper
Silicon dioxide (SiO2)
Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Not a rock, mineral, or geological specimen
Chert (Field Stone)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Chert (often called Flint or Jasper depending on color)
Chert (SiO2 - Microcrystalline or Cryptocrystalline Quartz)
Chert (Flint)
Silicon dioxide (SiO2)
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
Chert (Jasper/Agate variety)
Microcrystalline Quartz (SiO2)
Limestone / Dolomite
Calcium Carbonate (CaCO3) / Calcium Magnesium Carbonate (CaMg(CO3)2)
Chert (River Stone)
Microcrystalline Quartz (SiO2)
Coal (Bituminous or Anthracite)
Carbonaceous sedimentary rock (primarily Carbon, C)
Chert (Holey Stone)
Microcrystalline Quartz (SiO2)
Sandstone
Arenite (primarily composed of SiO2)
Quartz (Iron-Stained)
Silicon Dioxide (SiO2)
Yellow Chalcedony (Carnelian / Agate Pebbles)
Silicon Dioxide (SiO2)
Quartz (Milky / Clear Quartz Fragment)
Silicon Dioxide (SiO2)
Rose Quartz
Silicon dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Quartz (Milky/Common)
Silicon Dioxide (SiO2)
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
Fossiliferous Sandstone / Mudstone
Sedimentary Rock (Clastic with Fossiliferous Inclusions)
Limestone with Lichen
Carbonate Sedimentary Rock (primarily CaCO3)
Chert (specifically Red Chert / Jasper)
Silicon Dioxide (SiO2)
Chert (often called Flint or Jasper)
Cryptocrystalline quartz (SiO2)
Banded Chert
Microcrystalline Quartz (SiO2)
Chert (White Chert or Flint)
Microcrystalline or cryptocrystalline quartz (SiO2)
Chert (Yellow Jasper)
Microcrystalline Quartz (SiO2)
Banded Chert
Silicon Dioxide (SiO2)
Moldavite
Tektite (Silica Glass - SiO2 + Al2O3, FeO, MgO, CaO, Na2O, K2O)
Sandstone Concretion
Arenaceous concretion (primarily SiO2 with Fe2O3 staining)
Amber / Copal
Succinite (fossilized resin)
Bivalve Fossil (Fossilized Shell)
Class Bivalvia (fossilized in Calcium Carbonate/Aragonite)
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)