Rock Identifier

Category

Mineral (Biogenic Replacement)

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

Jasper (Chalcedony (cryptocrystalline quartz), SiO2) — Sedimentary

Jasper

Chalcedony (cryptocrystalline quartz), SiO2

Fossil Coral (Rugosa or Tabulata coral fossil (Calcite/Silica replacement)) — fossil

Fossil Coral

Rugosa or Tabulata coral fossil (Calcite/Silica replacement)

Pebble (likely Quartz or Chert) (SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.) — Sedimentary Rock

Pebble (likely Quartz or Chert)

SiO₂ (Silicon Dioxide) - referring to the likely main mineral composition, Quartz. If it's chert, the scientific name remains SiO₂ with a microcrystalline structure.

Sedimentary Rock

Chert (Chert (microcrystalline quartz)) — Sedimentary

Chert

Chert (microcrystalline quartz)

Chert / Flint (a variety of Chert) (Chert (SiO2)) — Sedimentary Rock (technically a microcrystalline quartz mineral aggregate)

Chert / Flint (a variety of Chert)

Chert (SiO2)

Sedimentary Rock (technically a microcrystalline quartz mineral aggregate)

Chert (or Flint) (Chert (a cryptocrystalline variety of quartz, SiO2)) — sedimentary

Chert (or Flint)

Chert (a cryptocrystalline variety of quartz, SiO2)

Leopard Skin Jasper (Chalcedony (cryptocrystalline quartz) with inclusions) — Mineral

Leopard Skin Jasper

Chalcedony (cryptocrystalline quartz) with inclusions

Tiger's Eye (Silicon dioxide (SiO2) with fibrous inclusions of crocidolite (riebeckite) that have been altered to limonite and then replaced by quartz) — Mineral

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite (riebeckite) that have been altered to limonite and then replaced by quartz

Turquoise (Turquoise (CuAl6(PO4)4(OH)8·4H2O)) — mineral

Turquoise

Turquoise (CuAl6(PO4)4(OH)8·4H2O)

Chert (varieties include Flint or Jasper) (Chert (cryptocrystalline quartz; SiO₂)) — Sedimentary

Chert (varieties include Flint or Jasper)

Chert (cryptocrystalline quartz; SiO₂)

Chert / Flint (Chert (varieties include Flint)) — Sedimentary

Chert / Flint

Chert (varieties include Flint)

Chert (Flint) (Chert (predominantly SiO₂ - silicon dioxide)) — sedimentary

Chert (Flint)

Chert (predominantly SiO₂ - silicon dioxide)

Red Jasper or Chert (Jasper (SiO2, a variety of chalcedony with iron oxide impurities), Chert (SiO2)) — sedimentary

Red Jasper or Chert

Jasper (SiO2, a variety of chalcedony with iron oxide impurities), Chert (SiO2)

Mixed Chalcedony and Jasper Bracelet (possibly 'Ocean Jasper' or similar banded variety for brown beads, and blue/grey Chalcedony for the translucent beads) (Chalcedony (SiO2), Jasper (SiO2 with impurities)) — Mineral (specifically a cryptocrystalline variety of Quartz)

Mixed Chalcedony and Jasper Bracelet (possibly 'Ocean Jasper' or similar banded variety for brown beads, and blue/grey Chalcedony for the translucent beads)

Chalcedony (SiO2), Jasper (SiO2 with impurities)

Mineral (specifically a cryptocrystalline variety of Quartz)

Fuchsite (Chromium-rich Muscovite (KAl2(AlSi3O10)(OH,F)2 with Cr replacements)) — mineral

Fuchsite

Chromium-rich Muscovite (KAl2(AlSi3O10)(OH,F)2 with Cr replacements)

Chert (often referred to as 'Jasper' when red) (Chert (microcrystalline quartz, SiO₂)) — Sedimentary rock

Chert (often referred to as 'Jasper' when red)

Chert (microcrystalline quartz, SiO₂)

Sedimentary rock

Pyrite (Pyrite (Iron sulfide, FeS₂)) — mineral

Pyrite

Pyrite (Iron sulfide, FeS₂)

Wood Jasper (Siliceous sedimentary rock (variety of Chert/Chalcedony)) — Sedimentary

Wood Jasper

Siliceous sedimentary rock (variety of Chert/Chalcedony)

Blue Chalcedony and Picture Jasper Beads (Blue Chalcedony (SiO2), Picture Jasper (SiO2)) — Mineral

Blue Chalcedony and Picture Jasper Beads

Blue Chalcedony (SiO2), Picture Jasper (SiO2)

Black Chert (Chert (microcrystalline quartz)) — Mineral

Black Chert

Chert (microcrystalline quartz)

Blue chalcedony cabochon (probable) (Chalcedony, cryptocrystalline quartz; silicon dioxide (SiO₂)) — gemstone

Blue chalcedony cabochon (probable)

Chalcedony, cryptocrystalline quartz; silicon dioxide (SiO₂)

Chert (or Flint) (Silicon dioxide (SiO2)) — sedimentary

Chert (or Flint)

Silicon dioxide (SiO2)

Red Jasper (beads) (Silicon Dioxide (SiO2) with iron inclusions) — Sedimentary Rock

Red Jasper (beads)

Silicon Dioxide (SiO2) with iron inclusions

Sedimentary Rock

Chert Pebble/Nodule (Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)) — Sedimentary

Chert Pebble/Nodule

Chert (a microcrystalline or cryptocrystalline sedimentary form of quartz, SiO2)

Silicified fossil-bearing limestone (likely chert/agate replacement) (Microcrystalline quartz (SiO₂) replacing carbonate rock; possible fossiliferous limestone) — sedimentary

Silicified fossil-bearing limestone (likely chert/agate replacement)

Microcrystalline quartz (SiO₂) replacing carbonate rock; possible fossiliferous limestone

Chert (variant of Flint) (Chert (SiO2)) — Sedimentary

Chert (variant of Flint)

Chert (SiO2)

Chert (Jasper Variant likely) (Silicon Dioxide (SiO2)) — Sedimentary Rock or Mineral (depending on origin and purity)

Chert (Jasper Variant likely)

Silicon Dioxide (SiO2)

Sedimentary Rock or Mineral (depending on origin and purity)

Tiger's Eye (Brown/Gold variety) (Pseudomorph of Quartz after Crocidolite (SiO2 with FeOOH inclusions)) — metamorphic

Tiger's Eye (Brown/Gold variety)

Pseudomorph of Quartz after Crocidolite (SiO2 with FeOOH inclusions)

Chert or Flint (polished/water-worn) (Chert (a microcrystalline or cryptocrystalline variety of quartz, SiO2). Flint is a specific variety of chert.) — Sedimentary (most likely, as Chert is a sedimentary rock often found as nodules in limestone or as bedded deposits; however, it can also form by metasomatic replacement, which leans towards metamorphic processes under certain conditions)

Chert or Flint (polished/water-worn)

Chert (a microcrystalline or cryptocrystalline variety of quartz, SiO2). Flint is a specific variety of chert.

Sedimentary (most likely, as Chert is a sedimentary rock often found as nodules in limestone or as bedded deposits; however, it can also form by metasomatic replacement, which leans towards metamorphic processes under certain conditions)

Pearl (Calcium carbonate (CaCO3) - mainly Aragonite with Conchiolin) — mineraloid

Pearl

Calcium carbonate (CaCO3) - mainly Aragonite with Conchiolin

Pearl (Aragonite / Calcium Carbonate (CaCO3)) — mineraloid

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Pearl (Aragonite and Conchiolin (CaCO3 + organic protein)) — mineraloid

Pearl

Aragonite and Conchiolin (CaCO3 + organic protein)

Black Pearl (Tahitian Type) (Aragonite / Conchiolin composite (CaCO3)) — mineraloid

Black Pearl (Tahitian Type)

Aragonite / Conchiolin composite (CaCO3)

Pearl (likely Freshwater or Akoya Cultured) (Aragonite / Conchiolin composite (CaCO3)) — Mineralloid (Organic gemstone)

Pearl (likely Freshwater or Akoya Cultured)

Aragonite / Conchiolin composite (CaCO3)

Mineralloid (Organic gemstone)

Pearl (Imitation or Cultured) (Calcium Carbonate (Aragonite/Calcite) - CaCO3) — Mineraloid (Organic)

Pearl (Imitation or Cultured)

Calcium Carbonate (Aragonite/Calcite) - CaCO3

Mineraloid (Organic)

Cat's Eye Shell (Shiva Shell) (Operculum of the Turbo petholatus (Tapestry Turban Snail), predominantly Calcium Carbonate (Aragonite)) — mineraloid / biogenic specimen

Cat's Eye Shell (Shiva Shell)

Operculum of the Turbo petholatus (Tapestry Turban Snail), predominantly Calcium Carbonate (Aragonite)

mineraloid / biogenic specimen

Shell Cameo (Cypraecassis rufa (Bullmouth Queen Helmet Shell)) — mineraloid / biogenic specimen

Shell Cameo

Cypraecassis rufa (Bullmouth Queen Helmet Shell)

mineraloid / biogenic specimen

Red Jasper (Silicon Dioxide (SiO2) with Hematite inclusions) — mineralological variety

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

mineralological variety

Red Jasper (Quartz (Silicon Dioxide) with Iron Oxide impurities (Fe2O3)) — mineralological specimen

Red Jasper

Quartz (Silicon Dioxide) with Iron Oxide impurities (Fe2O3)

mineralological specimen

Chert (specifically Silex or Flint) (Microcrystalline Quartz (SiO2)) — sedimentary

Chert (specifically Silex or Flint)

Microcrystalline Quartz (SiO2)