Mineral (Chalcedony)

Browse mineral (chalcedony) specimens identified by the Rock Identifier community.

Agate (or Banded Agate)

Agate (a variety of Chalcedony, which is a cryptocrystalline form of Quartz); Chemical Formula: SiO₂ (Silicon Dioxide)

Mineral, specifically a Cryptocrystalline Quartz variety

Quartz (likely Yellow/Orange variety, possibly Citrine or Chalcedony with iron staining)

Quartz (SiO₂)

Mineral

Chert (specifically Flint or Dark Chalcedony)

Silicon Dioxide (SiO2)

sedimentary

Chert (specifically Flint or Gray Chalcedony)

Microcrystalline Quartz (SiO2)

sedimentary

Agate (various color varieties)

SiO₂ (Silicon Dioxide)

Mineral (specifically a variety of Chalcedony, which is a microcrystalline quartz)

River Stone (Chalcedony/Jasper variety)

Microcrystalline Quartz (SiO2)

sedimentary

Brown Chalcedony (Agate/Jasper blend)

Silicon dioxide (SiO2)

sedimentary

Chert (Common Opal/Chalcedony mixture)

Silicon Dioxide (SiO2)

sedimentary

Banded Agate (likely Carnelian Agate or Sardonyx)

Agate is a common name for a microcrystalline variety of Quartz (SiO₂), specifically a form of Chalcedony.

Sedimentary Rock (technically a variety of Chalcedony)

Tiger's Eye (commonly referred to as Blue/Gold Tiger's Eye)

Tiger's Eye is a variety of Chalcedony (cryptocrystalline quartz), SiO2, exhibiting chatoyancy. The blue variety is often called Hawk's Eye.

Metamorphic Rock (formed from a fibrous crocidolite asbestos)

Chert (often called Flint or Chalcedony Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

sedimentary

Red Jasper (beads)

SiO₂ (Silicon Dioxide)

Mineral, variety of chalcedony (microcrystalline quartz)

Banded Agate (specifically Botryoidal/Orbicular Agate)

Silicon Dioxide (SiO2)

Mineral (variety of Chalcedony/Quartz)

Ocean Jasper (Orbicular Jasper)

Silicon Dioxide (SiO2) with iron and magnesium inclusions

Mineral (Variety of Quartz/Chalcedony)

Blue Lace Agate

Silicon Dioxide (SiO₂)

Mineral (Variety of Chalcedony/Quartz)

Red Jasper

Silicon Dioxide with Iron Oxide impurities (SiO2 + Fe2O3)

Mineral (variety of Chalcedony/Quartz)

Banded Chert / Banded Jasper (likely a variety of Chert/Chalcedony)

Chert (microcrystalline quartz)

Metamorphic Rock

Ocean Jasper (Orbicular Jasper)

Silicon Dioxide (SiO2) with various inclusions

sedimentary (geologically classified as a variety of chalcedony/quartz)

Massive Cryptocrystalline Quartz (Chert/Chalcedony Pebble)

Silicon Dioxide (SiO2)

sedimentary

Banded Iron Formation (Jasper-Hematite)

Banded Iron Formation (BIF); composition primarily Hematite (Fe2O3) and Chalcedony/Quartz (SiO2)

sedimentary

Tiffany Stone

Fluoritized Opal Beryllium Tuff (composed of Fluorite; CaF2, Opalized SiO2, Bertrandite, Chalcedony, and Quartz)

metamorphic

Red Swirl Beads (Likely Resin or Glass, simulating Red Jasper or Agate)

N/A (for the beads as pictured); Red Jasper: SiO2 (Chert variety); Red Agate: SiO2 (Chalcedony variety)

Organic (if resin) or Synthetic (if glass); simulating Sedimentary or Metamorphic (for natural stones)

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Chert (specifically Flint or Common Opal/Chalcedony mix)

Microcrystalline Quartz (SiO2)

sedimentary

Schist

Metamorphic

Mixed Agate and Lapis Lazuli Bracelet

Chalcedony (SiO2) and Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

sedimentary and metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Synthetic Resin (Artificial Specimen)

Polyurethane or Polyester Resin

mineraloid (man-made)

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

mineral

Granite

Phaneritic Plutonic Felsic Rock

igneous

Granite with Epidote

Granite, containing quartz, feldspar, and epidote

Igneous

Yooperlite (Sodalite-bearing Syenite)

Sodalite-rich Syenite

igneous

Orthoclase Feldspar with Quartz

Orthoclase (KAlSi3O8)

mineral

Basalt with Secondary Mineralization (Likely Zeolites or Calcite)

Aphanitic mafic volcanic rock with secondary mineral inclusions (e.g., CaAl2Si3O10·3H2O for Scolecite)

igneous

Fluorite

Calcium Fluoride (CaF2)

mineral

Sandstone

Sandstone (composed primarily of sand-sized minerals or rock grains)

sedimentary