Mineral, Specifically An Iron Ore

Hematite

Iron(III) oxide (Fe2O3)

Limonite / Goethite (Ironstone Nodule)

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

Limonite / Brown Iron Ore

Hydrous Iron Oxide (FeO(OH)·nH2O)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with ferric iron impurities)

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Ferruginous Quartz

Quartz (Silicon Dioxide) with Iron Inclusion, SiO2

Hematite

Iron(III) oxide (Fe2O3)

Orange mineral fragment, possibly iron oxide or carnelian

Uncertain; candidates include hematite/goethite (Fe₂O₃/FeO(OH)) or orange chalcedony (SiO₂)

Hematite

Iron(III) oxide (Fe2O3)

Yellow Jasper

Silicon Dioxide (SiO2) with iron inclusions

Limonite (Hydrated Iron Oxide / Bog Iron)

FeO(OH)·nH2O

Milky Quartz

Silicon Dioxide (SiO2)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Tumbled dark pebble, likely hematite or magnetite

Hematite (Fe₂O₃) or magnetite (Fe₃O₄); identification is uncertain from the image alone

Orange Calcite

Calcium Carbonate (CaCO3)

Limonite with Ironstone

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

Gold Ore

Native Gold (Au) in Matrix

Likely hematite-bearing ironstone

Hematite (Fe₂O₃), possibly mixed with other iron oxides and host rock

Tumbled iron-rich concretion or ironstone pebble

Goethite–hematite-rich ironstone; commonly limonite (FeO(OH)·nH₂O) with hematite (Fe₂O₃)

Limonite (Iron Ore)

Hydrated ferric oxide (FeO(OH)·nH2O)

Red Jasper

Jasper (Silicon Dioxide, SiO2)

Limonite Geode / Ironstone Concretion

Hydrated Iron Oxide (FeO(OH)·nH2O)

Copper Ore Specimen

Cupriferous Rock / Malachite-bearing ore

Limonite

FeO(OH)·nH2O

Weathered iron-rich stone, possibly limonite-bearing sandstone or laterite

Limonite/goethite-rich material; composition commonly FeO(OH)·nH₂O with clay and quartz impurities

Hematite

Hematite (Fe2O3)

Specular Hematite (Specularite)

Hematite (Alpha-Fe2O3)

Yellow Jasper

Silicon Dioxide (SiO2) with goethite or limonite inclusions

Magnetite / Ironstone Pebble

Magnetite (Fe3O4)

Likely iron-rich sulfide ore (possibly sphalerite with oxidized iron minerals)

Appearance may indicate sphalerite (ZnS) with limonite/goethite staining; identification from the image is uncertain.

Yellow Ochre

Goethite-rich clay (Hydrated Iron Oxide: FeO(OH)·nH₂O)

Carnelian

SiO2 (Silicon Dioxide) - Translucent reddish-brown variety of Chalcedony

Bog Iron (Limonite)

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

Vesicular basalt (possibly weathered amygdaloidal basalt)

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine, with weathering minerals filling vesicles

Weathered iron-rich rock fragment

Likely limonite/goethite-bearing rock; exact identification requires testing

Limonite (Yellow Ochre)

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

Weathered iron-rich rock, likely magnetite-bearing basalt or ironstone

Basalt/ironstone mixture dominated by iron oxides, chiefly magnetite (Fe3O4) and hematite (Fe2O3)

Pyrite or Chalcopyrite

Iron sulfide (FeS2) or Copper iron sulfide (CuFeS2)

Quartz (specifically Milky or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Small polished metallic mineral specimen

Indeterminate from image; possibly galena or hematite

Tree Agate

Chalcedony (SiO2) with Dendritic inclusions

Specular Hematite (Specularite) in Matrix

Specularite (Fe2O3)