Sedimentary (Chemically Precipitated Mineral)

Limonite (Limonitic Sandstone)

Hydrated Iron(III) Oxide-Hydroxide ($FeO(OH)·nH_2O$)

Banded Sedimentary Rock

Sedimentary rock with Liesegang banding

Quartz (Grain)

Silicon Dioxide (SiO2)

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrous iron oxides)

Tufa

Calcareous Tufa (CaCO3)

Wishing Stone (Basalt or Siltstone with Quartz/Calcite Vein)

Basalt (SiO2+MgO+FeO) or Siltstone with a Quartz (SiO2) or Calcite (CaCO3) vein

Sandstone with Ironstone Concretion

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

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Tumbled metallic sulfide mineral, likely pyrite

Pyrite (FeS₂), tentatively; possibly marcasite or a pyrite-rich nodule

Banded iron formation (ironstone), possibly hematite–magnetite-rich

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and chert/microcrystalline quartz (SiO₂)

Banded iron formation fragment (likely hematite–magnetite-rich ironstone)

Banded iron formation; chiefly hematite (Fe₂O₃), magnetite (Fe₃O₄), and silica/chert (SiO₂)

Amethyst Geode Fragment

Quartz (SiO2) with trace iron impurities

Tumbled dark stone, likely banded iron formation or hematite-rich jasper

Hematite-bearing quartz/jasper; probable iron oxide–silica aggregate

Weathered quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with iron-oxide staining

Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Opaque cryptocrystalline variety of Quartz

Limonite/goethite-rich ironstone concretion (probable)

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

Milky quartz crystal cluster

Quartz, silicon dioxide (SiO₂)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled chalcedony / quartz pebble

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

Likely iron-rich metamorphic rock (possibly hematite-rich ironstone)

Uncertain from the image; possible hematite-bearing ironstone, chiefly Fe₂O₃ with associated silicate minerals

Metallic sulfide ore, possibly pyrite-rich

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

Jasper

Silicon dioxide (SiO2) with iron impurities

Iron-rich jasper or ferruginous chert

Microcrystalline quartz (SiO₂) stained by iron oxides, chiefly hematite and goethite

Banded chert pebble

Chert (microcrystalline quartz, SiO₂), likely ribbon-banded chert

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Pyrite in Quartz Matrix

Iron Sulfide (FeS2) embedded in Silicon Dioxide (SiO2)

Sandstone (Picture Sandstone)

Arenite (primarily SiO2)

Quartz

SiO2 (Silicon Dioxide)

Ferruginous Sandstone

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

Quartz

Quartz (Silicon Dioxide, SiO2)

Botryoidal calcite (likely honey calcite)

Calcite — calcium carbonate, CaCO₃

Orange Calcite with Siderite/Iron Oxide Coating

Calcium Carbonate (CaCO3)

Banded Agate / Chalcedony

Cryptocrystalline Quartz (SiO2)

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Banded iron formation fragment

BIF; hematite–magnetite–chert/quartz assemblage

Quartz (Milky or Smoky Quartz variety)

Silicon Dioxide (SiO2)

Agate Geode

Silicon Dioxide (SiO2) - Chalcedony variety

Likely chert/flint fragment

Microcrystalline quartz (SiO₂), possibly partially weathered chert

Banded iron formation fragment

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

Dark flint or chert fragment

Microcrystalline quartz (SiO₂), likely chert/flint