Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Category
Organic (Geological Relative)
Browse organic (geological relative) specimens identified by the Rock Identifier community.
Prehnite
Prehnite, Ca2Al2Si3O10(OH)2
Mineral
Ironstone Concretion
Siderite or Hematite Concretion
sedimentary
Limestone
Calcium Carbonate (CaCO3)
sedimentary
Calcite
Calcite (CaCO3)
Mineral
Amber
Succinite (specific to Baltic amber), fossilized tree resin
mineraloid
Picture Jasper
Silicon Dioxide (SiO2) with iron oxide and organic impurities
sedimentary
Banded Chert
Microcrystalline silicon dioxide (SiO2)
sedimentary
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
Mineral (Variety of Chalcedony)
Peridot (Olivine)
Olivine, (Mg,Fe)2SiO4
Mineral
Quartz
Silicon Dioxide (SiO2)
Mineral
Quartz (Pebble)
Quartz (SiO₂)
Mineral
Fossilized Gastropod (Snail)
Class Gastropoda (internal mold or 'steinkern')
sedimentary
Black Marble with Quartz Veining
Metamorphosed Limestone (Recrystallized CaCO3)
metamorphic
Cobaltoan Calcite / Pink Dolomite (Possible)
Cobaltoan Calcite: (Ca,Co)CO3; Pink Dolomite (or Thulite): CaMg(CO3)2 or Mn-Dolomite / (Thulite: Mn2+3Al2(Si2O7)(SiO4)O(OH))
Mineral / Rock (depending on purity)
Arsenopyrite in Quartz Matrix
Arsenopyrite (FeAsS) with Quartz (SiO2)
Mineral in a Metamorphic/Hydrothermal rock
Sandstone (with carbonaceous plant fragments)
Arenite (composed primarily of SiO2)
sedimentary
Green Moss Agate
Silicon Dioxide (SiO2) with inclusions of hornblende or chlorite
sedimentary
Quartz (pebble)
Quartz (SiO₂)
Mineral
Opalite
Synthetic Opalised Glass
Mineral (Synthetic / Man-made)
Graphite
Graphite (Carbon, C)
Mineral
Carved Mottled Greenish-Yellow Crystal/Glass Object
Unknown; possibly a form of quartz (chalcedony/jadeite/nephrite) or glass/resin.
Man-made Object/Uncertain Mineral
Amygdaloidal Rhyolite (often called Lake Superior Agate relative)
Rhyolite with Calcite/Quartz amygdules (SiO2 and secondary minerals)
igneous
Pyrite
Iron Pyrite (FeS2)
mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Basaltic Tuff / Volcanic Breccia
Pyroclastic Breccia / Lithic Tuff
igneous
Quartz
Quartz (SiO₂)
Mineral
Quartz Geode
Silicon Dioxide (SiO2) within a secondary sedimentary structure
sedimentary
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Mineral
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Quartz Geode
Silicon Dioxide (SiO2)
sedimentary
Rose Quartz Carving
Quartum roseum (Variety of Quartz, SiO2)
Mineral
Zebra Marble
Metamorphosed Alabaster/Limestone (CaCO3)
metamorphic
Dendritic Opal (Common Opal)
Amorphous Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions
mineral
Red Jasper (beads)
SiO₂ (Silicon Dioxide)
Mineral, variety of chalcedony (microcrystalline quartz)
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
sedimentary
Ambergris
Physeter macrocephalus excreta (Ambergris)
mineraloid / organic geological find
Rose Quartz
Quartz (SiO2) with trace impurities causing pink color
Mineral
Chert (with Quartz vein)
Chert (Silicon Dioxide, SiO2)
sedimentary
Pyrite
Pyrite (Iron Disulfide), FeS2
Mineral
Banded Chert / Banded Jasper (likely a variety of Chert/Chalcedony)
Chert (microcrystalline quartz)
Metamorphic Rock
Wood Beads (Palmwood/Ebony)
Various species for wood, but often refers to woods like Palmwood (e.g., Borassus flabellifer) or Ebony (Diospyros spp.) for their distinctive grain and hardness.
Organic Gem Material (Botanical)