Geographic Minerals

Magadiite: Properties and Occurrences

Magadiite: Properties and Occurrences

Magadiite is a hydrous sodium silicate mineral [NaSi7O13(OH)3·4(H2O)] which precipitates from alkali brines as an evaporite phase. It is a soft white hydrous sodium silicate mineral. The mineral was first described by Hans P. Eugster in 1967 for an occurrence in Lake Magadi, Kenya, and is also f.....

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Madocite: Properties and Occurrences

Madocite: Properties and Occurrences

Madocite is a mineral with a general formula of Pb17(Sb, As)16S41. It is an orthorhombic-pyramidal grayish black mineral containing antimony, arsenic, lead, and sulfur. It is found in the marbles of the Precambrian Grenville Limestone. Madocite was named for the locality of discovery, Madoc, Onta.....

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Mackinawite: Properties and Occurrences

Mackinawite: Properties and Occurrences

Mackinawite is an iron-nickel sulfide mineral with formula (Fe, Ni)1+xS (where x = 0 to 0.11). It is a tetragonal iron-nickel sulfide mineral that occurs as opaque bronze to grey-white tabular crystals and anhedral masses. This corrosion compound is typically found in river sediment reducing envi.....

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Macdonaldite: Properties and Occurrences

Macdonaldite: Properties and Occurrences

Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4Si16O36(OH)2·10H2O. It is an orthorhombic-dipyramidal mineral containing barium, calcium, hydrogen, oxygen, and silicon. Macdonaldite was first described in 1965 and named for Gordon A. MacDonald (1911–1978) an Amer.....

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Macaulayite: Properties and Occurrences

Macaulayite: Properties and Occurrences

Macaulayite is a red, earthy, monoclinic mineral, with the chemical formula (Fe3+, Al)24Si4O43(OH)2. It is monoclinic blood-red mineral containing aluminum, hydrogen, iron, oxygen, and silicon. The substance is currently being studied by NASA, as it is speculated that this is the substance that g.....

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Lodestone: Properties and Occurrences

Lodestone: Properties and Occurrences

A lodestone is a naturally magnetized piece of the mineral magnetite. It is a piece of magnetite that has magnetic properties and attracts iron or steel. They are naturally occurring magnets, which can attract iron. It is an extremely rare form of the mineral magnetite that occurs naturally as a .....

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Limonite: Properties and Occurrences

Limonite: Properties and Occurrences

Limonite is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. It is a native hydrous ferric oxide of variable composition that is an ore of iron. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as .....

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Lignite: Properties and Occurrences

Lignite: Properties and Occurrences

Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It is a sedimentary rock that is formed from naturally compressed peat.  It is considered the lowest rank of coal due to its relatively low heat content. It has carbon.....

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Lechatelierite: Properties and Occurrences

Lechatelierite: Properties and Occurrences

Lechatelierite is silica glass, amorphous SiO2, non-crystalline mineraloid. This mineral is an amorphous form of silica formed by the fusion by the heat of silica and found in fulgurites. It is a mineral consisting of vitreous or glassy silica formed naturally by the melting of quartz sand as a r.....

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Larimar: Properties and Occurrences

Larimar: Properties and Occurrences

Larimar also called “Stefilia’s Stone”, is a rare blue variety of the silicate mineral pectolite found only in the Dominican Republic, in the Caribbean. Its coloration varies from white, light-blue, green-blue to deep blue. It is a volcanic stone, the result of volcanic activity.....

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Lapis lazuli: Properties and Occurrences

Lapis lazuli: Properties and Occurrences

Lapis lazuli or lapis for short is a deep-blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color. It is characterized as a sodium aluminum silicate made up of Lazurite, Sulfur, Chlorine, and Hydroxyl. It’s deep, celestial blue remains .....

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Lyonsite: Properties and Occurrences

Lyonsite: Properties and Occurrences

Lyonsite [Cu3Fe3+4 (VO4)6] is a rare black vanadate mineral that is opaque with a metallic luster. It is an orthorhombic-dipyramidal black mineral containing copper, iron, oxygen, and vanadium. It was first described in 1987 for an occurrence on the Izalco volcano, El Salvador. It was named for m.....

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