Limestone
CaCO3 (principally Calcite)
Category
Browse metamorphic or sedimentary depending on local grade specimens identified by the Rock Identifier community.
Limestone
CaCO3 (principally Calcite)
Quartz (Milky/Crystalline)
Silicon Dioxide (SiO2)
Chert (Jasper variety)
Cryptocrystalline quartz (SiO2)
Quartz (likely a weathered/tumbled piece)
Quartz (SiO₂)
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Blue Sapphire
Corundum (Al2O3 with trace Titanium and Iron)
Anthracite Coal
Anthracite
Anthracite Coal
Anthracite
Anthracite Coal
Anthracite
Greenstone
Greenschist (containing chlorite, epidote, and actinolite)
Nuummite
Nuummite (Orthoamphibole rock composed of Anthophyllite and Gedrite)
Anthracite Coal
Anthracite (Carbon-rich metamorphic rock)
Greenstone
Metabasalt / Metamorphosed Igneous Rock
Anthracite Coal
Anthracite (high-rank coal / Carbon)
Hag Stone
Sandstone or Limestone with Solution Holes (Bioturbation/Erosion)
Bornite
Bornite (Cu5FeS4)
Green Aventurine
Quartz variant (SiO2) with Fuchsite inclusions
Bornite (Peacock Ore)
Bornite (Cu5FeS4)
Agate (Plume/Moss variety)
Cryptocrystalline Quartz (SiO2) with iron/manganese inclusions
Geode with Quartz and Chalcedony
Silicon Dioxide (SiO2)
Chert (Flint)
Cryptocrystalline Quartz (SiO2)
Hag Stone (Sandstone with Boreholes)
Bored Sandstone (Sedimentary rock with lithophaga-style borings)
Mica Schist
Mica Schist (Composition typically includes Muscovite KAl2(AlSi3O10)(OH)2 and Quartz SiO2)
Jadeite
NaAlSi2O6 (Sodium Aluminum Silicate)
Serpentinite
Serpentinite (group of minerals: Antigorite, Lizardite, Chrysotile)
Emerald in Matrix (Quartz/Schist)
Beryl (Be₃Al₂Si₆O₁₈) with Chromium/Vanadium impurities
Diamond
Carbon (C), Native Element
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals, (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4)
Muscovite Mica
Muscovite (KAl₂(AlSi₃O₁₀)(F,OH)₂))
Almandine Garnet
Almandine (Fe3Al2(SiO4)3)
Rhodolite Garnet
Mg3Al2(SiO4)3 - Fe3Al2(SiO4)3 (Pyrope-Almandine series)
Blue Sapphire (in a faceted jewelry setting)
Corundum (Al2O3) with trace Iron and Titanium
Moonstone
Adularia (orthoclase) or Albite (plagioclase), a potassium aluminum silicate of the feldspar group
Quartz (Rock Crystal)
Quartz (SiO₂ - Silicon Dioxide)
Quartz (likely milky/gray variety)
Quartz (SiO₂)
Talc
Talc (Mg₃Si₄O₁₀(OH)₂)
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Carnelian (Orange Agate)
Silicon Dioxide (SiO2)
Common Opal / Chert
Hydrated silica (SiO2·nH2O) or Microcrystalline Quartz (SiO2)
Sandstone or Mudstone
Sedimentary Rock (Sandstone/Mudstone)
Corundum (Sapphire and Ruby)
Aluminum Oxide (Al2O3)