Oxide Minerals
Oxide minerals form a distinctive and essential class of minerals in which oxygen (O²⁻) bonds directly with one or more metal (or semi-metal) cations, producing compounds that often crystallize in igneous environments, during metamorphism or as weathering products at Earth’s surface. These include well-known species such as hematite (Fe₂O₃), magnetite (Fe₃O₄), corundum (Al₂O₃) and chromite (FeCr₂O₄). Because of their relatively simple chemistry compared to silicates and their varied formation settings, oxide minerals provide crucial clues about temperature, oxidation state, fluid history and tectonic processes. They are also directly tied to major ore deposits — for example iron ores, chromium ores and aluminium ores often occur as oxides. In this category you’ll explore how oxide minerals form, how their crystal structures and physical properties reflect those formation conditions, where they occur in the field (or in the subsurface) and why as a geologist, engineer or site-practitioner you should pay attention to them for everything from exploration to material behaviour and geotechnical risk.
Rutile
Rutile is oxide group mineral with formula: titanium dioxide (TiO2). It often appears as pale golden, needlelike crystals inside quartz. When not enclosed in quartz, it is usually yellowish or reddish brown, dark brown, or black.
Brucite
Brucite is a mineral that is composed of magnesium hydroxide (Mg(OH)2). It belongs to the class of minerals known as hydroxides, which are compounds...
Crocoite
Crocoite is a rare mineral classified as a lead chromate (PbCrO₄). It is well-known for its vibrant orange-red color and distinctive crystal formations, which...
Musgravite
Musgravite is a rare and precious gemstone that belongs to the oxide mineral family. It is a member of the taaffeite family, which also...
Chromite
Chromite is an oxide mineral that an iron chromium oxide with formula: FeCr2O4. It is belonging to the spinel group. Chromite is the most important ore of chromium. Crystals are uncommon, but when found they are octahedral. Chromite is usually massive or in the form of lenses and tabular bodies, or it may be disseminated as granules.
Alexandrite
Among all gemstones studied by mineralogists and gemologists, alexandrite remains one of the most scientifically fascinating. It is a variety of the mineral chrysoberyl...
Diaspore
Diaspore, an aluminum hydroxide mineral with the chemical formula AlO(OH), is a fundamental component in the study of geology and mineralogy. It is significant...
Gibbsite
Gibbsite is a naturally occurring mineral form of aluminum hydroxide with the chemical formula Al(OH)₃. It belongs to the hydroxides and oxides mineral class...
Goethite
Named after the German mineralogist Johann Wolfgang von Goethe in 1806, goethite is a common mineral. It can be brownish yellow, reddish brown, or dark brown in color, depending on the size of the crystal in the specimen—small crystals appear lighter, and larger ones darker.
Gahnospinel
Gahnospinel is a mineral belonging to the spinel group, which is a class of minerals with the general formula AB₂O₄. In gahnospinel, A represents...
Rosasite
Rosasite is a secondary mineral that typically forms in oxidized zones of copper-zinc ore deposits. It is chemically composed of copper zinc carbonate hydroxide,...
Pink Star Sapphire
Pink star sapphires are a captivating variety of sapphire known for their stunning pink hues. Sapphires are a type of corundum mineral, with their...
