Organic (Geological Interest)

Siltstone with Quartz Vein

Siltstone (composed of Quartz and Clay minerals) with a hydrothermal Quartz vein (SiO2)

Granite fragment

Phaneritic Igneous Rock (Granitic composition)

Limonite (Ironstone)

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

Limonite Concretion

Limonite (Hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)

Sandstone with Iron Staining

Arenite (SiO2 with Fe2O3)

Quartz Vein in Pelite (Metamorphic Rock)

Hydrothermal Quartz Veining in Metasedimentary Rock (SiO2)

Sandstone with Foliose Lichen

Arenite (Rock matrix) with Xanthoparmelia or Flavoparmelia (Lichen genus)

Porphyritic Andesite or Dacite (tumbled pebble)

Porphyritic Igneous Rock (likely Andesite or Dacite)

Ferruginous Quartzite (also known as Ironstone or Gossan)

Ferruginous Quartzite with Goethite/Hematite staining

Basalt with Caliche Crust

Aphanitic Mafic Igneous Rock with Calcium Carbonate (CaCO3) coating

Limonite with Quartz

FeO(OH)·nH2O (Limonite) with SiO2 (Quartz)

Ironstone Concretion

Ironstone (primarily Siderite or Limonite / Goethite, FeO(OH)·nH2O)

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

Amygdaloidal Basalt

Amygdaloidal Basalt (Mafic volcanic rock)

Basalt with Desert Varnish

Mafic Igneous Rock with Ferromanganese Coating

Chert (Pebble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartz-rich metamorphic rock, likely quartzite or vein quartz

Quartzite; predominantly microcrystalline quartz (SiO₂), possibly with mica and feldspar

Quartz Vein in Host Rock

Crystalline Silicon Dioxide (SiO2) in Pelitic or Shaly Matrix

Mica Schist

Foliated Metamorphic Rock (rich in Muscovite or Biotite)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz with Iron Staining

Silicon Dioxide (SiO2) with Hematite inclusions

Limonite

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

Limonite (after Pyrite Pseudomorph)

Limonite (Hydrated Iron Oxide Mixture, FeO(OH)·nH2O)

Quartzite (Ferruginous)

Metamorphosed Quartz Sandstone (SiO2 with Iron oxide staining)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) in Altered Host Rock

Unidentified rock fragments

Indeterminate; likely a weathered, iron-stained silicate rock

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Quartz (Smoky/Milky variant)

Silicon Dioxide (SiO2)

Mica-rich Sandstone or Micaceous Schist Weathering

Micaceous Schist (Muscovite-Quartz composition)

Quartz (likely Chalcedony or Chert)

Silicon Dioxide (SiO2)

Quartz with Iron Oxide Inclusions

SiO2 with Fe2O3 impurities

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Pearl (with Peridot)

Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4

Peridotite

Ultramafic intrusive igneous rock

Iron-rich Gossan with Quartz

Limonite and Goethite with Silicon Dioxide (SiO2)

Milky or Greenish Quartz Pebble

Silicon Dioxide (SiO2)

Gneiss (specifically a Granitic Gneiss)

Gneiss (Composition: Quartz, Feldspar, Mica)

Pyrite

Iron Disulfide (FeS2)

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Weathered brown rock fragment

Indeterminate; possibly ferruginous sandstone or weathered volcanic rock

Quartz-veined Basalt

Amygdaloidal or Porphyritic Basalt with Silicon Dioxide (SiO2) vein

Sandstone (Pebble)

Arenite / Clastic Sedimentary Rock