Sedimentary (Chemically Precipitated Mineral)

Clear quartz

Quartz (silicon dioxide, SiO₂)

Banded iron formation fragment

BIF; hematite–magnetite–chert/quartz assemblage

Botryoidal calcite (likely honey calcite)

Calcite — calcium carbonate, CaCO₃

Quartz Pebble

Silicon Dioxide (SiO2)

Banded Agate / Chalcedony

Cryptocrystalline Quartz (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Weathered iron-rich concretion or sedimentary rock

Likely ferruginous sandstone or ironstone concretion; exact identification is not possible from the image alone

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone with Ironstone Concretion

Arenite with Hematite/Goethite nodules (Fe2O3 / FeO(OH))

Chert (Field Stone)

Microcrystalline Quartz (SiO2)

Tufa

Calcareous Tufa (CaCO3)

Jasper

Microcrystalline Quartz (SiO2)

Druzy quartz on matrix

Quartz (SiO₂), likely microcrystalline-to-fine crystalline drusy quartz

Banded iron formation fragment

Banded iron formation (BIF), composed mainly of hematite/magnetite and chert (SiO₂)

Banded Calcite (Onyx Marble / Travertine)

Calcium Carbonate (CaCO3)

Calcite crystal cluster

Calcite (calcium carbonate, CaCO₃), likely honey or pale-orange calcite

Quartz (Microcrystalline variety)

Silicon Dioxide (SiO2)

Dark flint or chert fragment

Microcrystalline quartz (SiO₂), likely chert/flint

Polished banded iron formation (BIF)

Banded iron formation; chiefly hematite/magnetite and microcrystalline quartz (chert), with iron silicates

Jasper

Silicon dioxide (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Opaque cryptocrystalline variety of Quartz

Aragonite (Flos Ferri)

Calcium Carbonate (CaCO3)

Sandstone (Picture Sandstone)

Arenite (primarily SiO2)

Quartz (Common or Milky Quartz)

Silicon Dioxide (SiO2)

Tumbled chalcedony / quartz pebble

Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide staining

Limonite/goethite-rich ironstone concretion (probable)

Goethite–limonite, chiefly FeO(OH)·nH₂O, possibly with hematite and manganese oxides

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz (Milky/Bull Quartz)

Silicon Dioxide (SiO2)

Ferruginous Sandstone

Arenite with Iron-Oxide Cement (SiO2 with Fe2O3/FeO(OH))

Metallic sulfide ore, possibly pyrite-rich

Pyrite (FeS₂), potentially mixed with chalcopyrite, galena, or iron oxides

Clear Quartz

Silicon dioxide (SiO2)

Tumbled dark sulfide-rich mineral specimen (possibly pyrite/marcasite)

Tentatively iron disulfide, FeS₂; exact identification requires testing

Aragonite

Aragonite (Calcium Carbonate - CaCO3)

Quartz (Milky or Smoky Quartz variety)

Silicon Dioxide (SiO2)

Specular Hematite

Hematite (Fe2O3)

Weathered stone, likely sandstone or altered volcanic rock

Indeterminate; possibly quartz-rich sandstone or weathered tuff

Tumbled milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz pebble

Quartz, silicon dioxide (SiO₂), microcrystalline to coarsely crystalline variety

Milky quartz pebble

Quartz, silicon dioxide (SiO₂)

Weathered flint (chert) pebble

Microcrystalline quartz, SiO₂ (flint/chert)

Quartz Geode

Silicon Dioxide (SiO2)