Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Turquoise-bead jewelry

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O; the beads may be natural turquoise or a stabilized/imitation material

River Pebble (Quartz/Jasper)

Silicon Dioxide (SiO2)

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

Botryoidal Goethite

Goethite (α-Fe3+O(OH))

Copper Ore Bearing Rock

Host rock with secondary copper minerals (such as Malachite, Azurite, and Chrysocolla)

Gray rock (possibly basalt or fine-grained granite)

Undetermined; no diagnostic minerals are visible

Limonite Boxwork / Iron Ore Concretion

FeO(OH)qnH2O (Hydrated iron oxide)

River Quartz Pitting/Cobble

Silicon Dioxide (SiO2)

Banded Agate

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Limonite with Hematite

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

Basalt with Vesicular Surface

Basalt (Mafic Extrusive)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Limonite/Hematite Ironstone

Goethite-rich Ironstone (FeO(OH) · nH2O)

Weathered jasper-rich ironstone

Siliceous ironstone, likely jasper/chert with hematite and goethite

Limonite or Ironstone

Hydrated iron oxide-hydroxide, approximately FeO(OH)·n(H2O)

Limonite (Iron Ore)

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

River Stones (Quartzite and Sandstone)

Quartzite / Sedimentary Rock (SiO2 dominant)

Hematite

Iron Oxide (Fe2O3)

Limonite (Iron Ore)

Limonite (Hydrous iron(III) oxide-hydroxide mixture, primarily FeO(OH)·nH2O)

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Chalcedony (Agate / Moss Agate)

Silicon Dioxide (SiO2)

Likely rough metallic meteorite fragment

Unclassified iron or stony-iron meteorite; identification is uncertain from the image alone

Red Siltstone

Siltstone (composed mainly of SiO2 and Fe2O3)

Iron-rich meteorite fragment (probable stony-iron or iron meteorite)

Unclassified Fe–Ni meteorite; possible weathered iron meteorite

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Hematite

Iron(III) oxide, Fe2O3

Limonite

Limonite (Hydrous iron oxides, FeO(OH)·nH2O)

Limonite with Hematite

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

Limonite / Ironstone

Hydrated Iron Oxide (FeO(OH)·nH2O)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated Iron Oxide)

Weathered, biotite-bearing granite or granitic gneiss

Quartz–feldspar–biotite rock; likely granite (compositionally, quartz + K-feldspar/plagioclase + biotite), possibly weakly foliated gneiss

Limonite (Iron Ore)

Limonite (mixed iron hydroxides, primarily FeO(OH)·nH2O)

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Limonite (Goethite/Ironstone)

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

Weathered basalt pebble with a vesicle

Basalt (fine-grained mafic volcanic rock; commonly plagioclase, clinopyroxene, and Fe-Mg oxides)

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2) with various iron-oxide inclusions

Limonite with Hematite

Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)

Iron-stained quartz-bearing rock, possibly weathered granite or pegmatite

Quartz-rich felsic rock with iron oxyhydroxides (goethite/limonite); exact classification requires testing

Jasper with Purple Fluorite or Chalcedony

Silicon Dioxide (SiO2) with mineral inclusions

Blue opalite (often sold as synthetic opal)

Opalite glass; amorphous hydrated silica if natural opal (SiO₂·nH₂O)

Chalcedony (Agate / Quartz Pebble)

Silicon Dioxide (SiO2)