Mineral (Sedimentary Context)

Flint

SiO2 (Microcrystalline Quartz / Chert)

Sandstone (with Iron Staining)

Arenite

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

White Marble

Recrystallized Calcite (CaCO3)

Pyrite

Iron Sulfide (FeS2)

Angelite

Anhydrous Calcium Sulfate (CaSO4)

Magnetite / Iron Ore

Magnetite (Fe3O4)

Marble

Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)

Limonite

FeO(OH)·nH2O

Limonite / Goethite (Ironstone Nodule)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Quartz Pebble

Silicon Dioxide (SiO2)

Yellow Apatite

Fluorapatite (Ca5(PO4)3(F,Cl,OH))

Rounded quartz-rich pebble

Probable arkosic sandstone or weathered quartzite; exact identification is uncertain from the image

Ironstone Concretion (Moqui Marble / Boji Stone)

Sedimentary Iron Oxide Concretion (Fe2O3 / FeO(OH))

Sandstone

Arenite (SiO2 dominant)

Clear Quartz

Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Epidote

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

Limonite or Ironstone Nodule

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)

Sandstone (with man-made markings)

Arenite (composed primarily of Quartz, SiO2)

Pyrite (likely)

Pyrite, iron sulfide (FeS₂)

Quartzwacke / Impure Sandstone

Arenite with minor lithic fragments (Silicon Dioxide matrix)

Weathered graywacke or sandstone fragment

Lithic sandstone, likely quartz–feldspar–rock-fragment aggregate

Likely biotite-rich schist or gneiss

Mica schist (quartz–feldspar–biotite assemblage; exact identification requires examination)

Jasper with Quartz Vein

Silicon Dioxide (SiO2)

Yellow Ochre (Limonite)

Limonite (FeO(OH)qnH2O)

Rhodochrosite

Manganese Carbonate (MnCO3)

Chalcopyrite

Copper iron sulfide (CuFeS2)

Limonite or Ironstone Nodule

Hydrated iron oxide-hydroxide (FeO(OH)·nH2O)

Limonite Nodule

FeO(OH)·nH2O (Hydrated iron oxide-hydroxide)

Limonite

FeO(OH)·nH2O

Sandstone pebble

Sandstone (mainly Quartz, SiO2)

Coarse-grained gray metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss (probable)

Limonite (Iron Ore)

Limonite; FeO(OH)·nH2O

Milky quartz

Quartz (silicon dioxide, SiO₂)

Tumbled quartz pebble

Quartz (silicon dioxide, SiO₂), probably milky or iron-stained quartz

Rough amber-colored quartz or calcite fragment

Likely quartz (SiO₂) or calcite (CaCO₃); exact identification requires testing

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Limonite

FeO(OH)·nH2O (Hydrated iron oxide-hydroxide)

Limonite

FeO(OH)·nH2O

Limonite (Ironstone Concretion)

Limonite (FeO(OH)·nH2O)