Mineral (Iron Ore)

Chert (Iron-stained)

Chert (Microcrystalline Quartz, SiO2)

Quartz with Iron Staining

Silicon Dioxide (SiO2) with Ferruginous Oxides

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Sandstone Concretion

Clastic Sedimentary Concretion (primarily SiO2 with Fe2O3 cement)

Tiger's Eye

Tiger's Eye (Pseudomorph of Quartz after Crocidolite), SiO2

Ferruginous Quartz

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Metal Alloy (Likely Pewter or Sterling Silver)

Not a natural geological specimen; composed of refined metals. If pewter, it's a tin-based alloy. If sterling silver, it's 92.5% silver and 7.5% other metals (usually copper).

Red Ochre (Hematite-rich Clay)

Limonitic/Hematitic Claystone (Fe2O3 with clay minerals)

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Ferruginous Quartz

Quartz (Silicon Dioxide, SiO2) with Iron Oxides

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

Pyrite

Iron Sulfide (FeS2)

Nephrite Jade

Nephrite

Lepidolite (likely)

K(Li,Al)3(Al,Si)4O10(F,OH)2 (Phyllosilicate mineral, part of the mica group)

Tiger's Eye (with Hematite/Jasper)

SiO2 (Silicon Dioxide) with Fe2O3 (Hematite)

Pegmatite (likely Granitic Pegmatite)

Pegmatite (a coarse-grained igneous rock, often with granitic composition)

Yellow Jasper

SiO2 (Silicon Dioxide)

Rose Quartz with Hematite inclusions

Silicon Dioxide (SiO2) with Fe2O3 inclusions

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2) with iron oxide inclusions (Limonite/Hematite)

Pyrite

Iron Sulfide (FeS2)

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Basalt with Weathering Crust

Extrusive mafic volcanic rock

Jasper (Iron-stained Quartzite/Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Sandstone (Ferruginous)

Arenite with Iron Oxides

Fossil / Permineralized Bone

Tyrannosaurus rex fossil (Hydroxylapatite replaced by various minerals)

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Marble

Recrystallized Calcite (CaCO3)

Olivine (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Ironstone Concretion (Moqui Marble variety)

Ferruginous Sandstone Concretion

Olivine in Basalt (Peridotite Xenolith)

Forsterite-rich Olivine (Mg2SiO4) in Aphanitic Basalt

Limonite-stained Quartz

Silicon Dioxide (SiO2) with Iron Oxide/Hydroxide (FeO(OH)·nH2O) staining

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3/FeO(OH)) inclusions

Quartz with Limonite Staining

Silicon Dioxide (SiO2) with Hydrated Iron Oxide (FeO(OH)·nH2O)

Serpentinite

Serpentinite

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Bauxite

Bauxite (Principal ore of aluminum; mixture of minerals including Gibbsite Al(OH)3, Boehmite and Diaspore AlO(OH))

Ferruginous Quartz

SiO2 (Silicon Dioxide) with Iron Oxide inclusions (FeO(OH) / Fe2O3)

Ferruginous Quartzite (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Ferric Oxide (Fe2O3)

Sandstone or Quartzite

Arenite (if sedimentary) / Quartzite (if metamorphic)

Basalt with Iron Oxidation

Mafic Igneous Rock (Basalt)