Mineraloid (Human Made Geological Specimen)

Chert

Microcrystalline Quartz (SiO2)

This image does not display a rock, mineral, or geological specimen. It shows a human hand wearing a ring.

N/A

Natural Pearl

Calcium carbonate (primarily Aragonite and Conchiolin), CaCO3

Snowflake Obsidian

Volcanic Glass with Spherulite Inclusions (70-75% SiO2)

Boulder Opal

Hydrated Silica (SiO2·nH2O)

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

gemstone

Quartz (Pebble)

Quartz (SiO₂)

Mineral

Chert / Flint

Chert (varieties include Flint)

Sedimentary

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Flint / Chert (Beach-worn Pebble)

Microcrystalline quartz (SiO2)

Chert (Nodule)

Microcrystalline Quartz (SiO2)

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Polymictic breccia, possibly volcanic breccia

Polymictic clastic breccia; likely a matrix-supported breccia containing lithic fragments, quartz, feldspar, and dark mafic minerals

Gemstone bead necklace (likely citrine or yellow quartz)

Quartz, SiO₂; precise identification is uncertain because the beads are blurred and metal settings obscure them

gemstone

Obsidian

Volcanic Glass (Amorphous SiO2)

Chert Concretion (with typical hematite/limonite staining)

Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)

Chert / Flint

Silicon Dioxide (SiO2)

Aura Quartz

Titanium-coated Silicon Dioxide (SiO2)

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Pearl (Biogenic Mineral)

Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3

Limonite (Ironstone)

Limonite (mixture of hydrated iron(III) oxide-hydroxides)

Common Opal in Host Rock

Hydrated Silica (SiO2·nH2O)

Chert / Flint Handaxe

Cryptocrystalline Quartz (SiO2)

Obsidian

Amorphous volcanic glass (SiO2)

Flint / Chert

Microcrystalline Quartz (SiO2)

Fulgurite

Liesegang (Fulgurite)

Mineraloid

Granite Pebble

Felsic intrusive igneous rock

Bumblebee Jasper

Anhydrite-Aragonite mixture with Orpiment and Realgar

Fulgurite

Luechatelierite (SiO2 glass)

Chert / Flint

Silicon Dioxide (SiO2)

Chert

Sedimentary cryptocrystalline quartz (SiO2)

Chert / Flint (Flaked Stone Tool / Projectile Point)

Microcrystalline Quartz (SiO2)

Mahogany Obsidian

Volcanic Glass with Hematite (SiO2 + Fe2O3)

Amber / Copal

Succinite (fossilized tree resin)

Flint / Chert Pebble

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline quartz (SiO2)

Pink quartz bead necklace/strand

Quartz, silicon dioxide (SiO₂), likely rose quartz or pink chalcedony; exact identification is uncertain from the image

gemstone

Amber / Copal

Succinite (fossilized resin)

Chert (Flint / Jasper variant)

Microcrystalline Quartz (SiO2)

Painted Garden Rock

Coated Siltstone or Mudstone