Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Quartz (Chert/Chalcedony Variety)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primary component SiO2)

Greenschist

Greenschist (containing Chlorite, Actinolite, and Epidote)

Weathered iron-rich metamorphic rock (probable amphibolite or schist fragment)

Likely hornblende–plagioclase amphibolite with biotite/chlorite alteration; exact identification requires testing

Limonite Geode / Ironstone Concretion

Hydrated Iron Oxide (FeO(OH)·nH2O)

Copper Ore

Native Copper (Cu) often found with Chalcocite (Cu2S) or Bornite (Cu5FeS4)

Banded gneiss (likely garnet-biotite or quartz-feldspar gneiss)

Gneiss; predominantly quartz (SiO₂), feldspar, and dark biotite/amphibole

Stony-Iron Meteorite (likely Mesosiderite or Ordinary Chondrite)

Meteorite (Silicate-Metal Matrix)

Gossan (Iron Cap)

Limonitic Gossan (Fe2O3·nH2O mixed)

Quartz Pebble

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Milky or Yellow/Citrine Quartz)

Silicon Dioxide (SiO2)

Hematite / Goethite (Iron Ore)

Iron Oxide (Fe2O3 / FeO(OH))

Hematite (Iron Ore)

Hematite (Fe2O3)

Weathered vesicular basalt

Basalt, chiefly plagioclase and pyroxene with secondary iron oxides and zeolite/calcite fillings

Limonite (Iron Stone Concretion)

Limonite (Hydrous Iron Oxide) - FeO(OH)·nH2O

Iron-stained weathered rock

Unknown

Agate (Chert/Chalcedony)

Silicon Dioxide (SiO2)

Amber-bearing rough specimen

Fossilized plant resin (amber; organic mineraloid), commonly succinite

Yellow Ocherous Siltstone (Limonitic Shale)

Limonitic Siltstone / Goethite-rich Sedimentary Rock

Likely iron meteorite fragment

Iron–nickel meteorite, commonly kamacite–taenite (Fe–Ni alloy)

Mica Schist with Iron Staining

Muscovite/Biotite Schist

Rough amber-colored quartz or calcite fragment

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

Limonite (Gossan)

FeO(OH)·nH2O (Hydrated Iron Oxide)

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Ironstone / Weathered Hematite

Iron oxide-rich sedimentary rock with Goethite/Hematite

Dalmatian jasper

Spotted rhyolite (commercially called Dalmatian jasper), chiefly quartz and feldspar with black aegirine/arfvedsonite inclusions

Biotite-rich granite or granodiorite

Coarse-grained granitoid, primarily quartz, plagioclase/feldspar, and biotite mica

Yellow Quartz (Chalcedony)

Silicon Dioxide (SiO2)

Copper-bearing oxidized rock

Likely malachite–chrysocolla with limonite/goethite in a weathered host rock; exact identification requires testing

Turquoise

Turquoise - CuAl6(PO4)4(OH)8·4H2O

Polished red gemstone pendant, likely red jasper or brecciated jasper

Jasper: microcrystalline quartz (SiO₂), commonly with hematite or iron-oxide inclusions

Sandstone

Arenite (SiO2 secondary)

Agate (Chalcedony)

Silicon Dioxide (SiO2)

Quartz-rich geode or mineralized cavity in host rock

Likely a quartz-bearing geode; the pale crystals may be quartz (SiO₂), but the photo is not detailed enough for a firm identification.

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Chalcedony (Agate/Carnelian pebbles)

Cryptocrystalline Quartz (SiO2)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Iron-stained Quartz

Silicon Dioxide with Limonite (SiO2 + FeO(OH)·nH2O)

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2)

Quartz pebble

Silicon dioxide (SiO2)

Iron-stained Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite inclusions