Molybdenum

Chemical formula: Mo

Native molybdenum is a rare mineral and chemical element, occurring as metallic, silvery-white grains and flakes.

## Characteristics Native molybdenum is a chemical element and a mineral from the native elements group. It occurs extremely rarely as small, most often microscopic, inclusions in rocks. Typical specimens are in the form of fine, irregular grains, platelets, or flakes with a metallic, silvery-white or gray color. Due to its size and rarity, it does not form visually spectacular specimens, and its significance is primarily scientific. ## Physical Properties This mineral is soft and malleable, meaning it can be easily scratched and deformed. It is characterized by very high density, which is noticeable even in small fragments. The luster is strongly metallic, and the mineral itself is completely opaque. ## Colors and Varieties Native molybdenum has a constant color – from silvery-white to tin-white or lead-gray. On fresh surfaces, it is brighter, but over time it may slightly tarnish. No color or commercial varieties are distinguished. ## History and Name The name "molybdenum" comes from the Greek word "molybdos" (μόλυβδος), meaning lead. In ancient times, this term was used to describe various substances with a metallic appearance and high density, including galena and graphite. The pure element molybdenum was first isolated by Peter Jacob Hjelm in 1781. As a mineral, native molybdenum was described in later years from various locations, but its status as a distinct mineral species was repeatedly verified due to its extreme rarity. ## Uses Native molybdenum has no direct industrial application due to its extreme rarity. However, it is an object of scientific and collecting interest. Industry obtains molybdenum on a massive scale from its sulfide – molybdenite (MoS₂), which is the main source of this metal. Molybdenum is primarily used as an alloying additive to steel, increasing its hardness, strength, and corrosion resistance.

Properties

Mohs hardness: 4
Luster: Metallic
Streak: Gray
Density: 10.28
Cleavage: None
Fracture: Hackly
Transparency: Opaque
Crystal system: Cubic

Diagnostic features

## Identification Identifying native molybdenum is difficult due to its microscopic size and similarity to other metallic minerals. Key features include silvery-white color, strong metallic luster, high density, and softness. Identification usually requires advanced laboratory methods, such as EDS analysis in a scanning electron microscope (SEM). ## Distinguishing from Similar Minerals Native molybdenum can be confused with native platinum, native silver, native lead, or native tin. Distinguishing it "by hand" is practically impossible. In laboratory conditions, its chemical composition differentiates it. From the much more common molybdenite, it differs by the lack of cleavage and a brighter, more silvery color (molybdenite is more bluish-gray). ## Crystal Forms It crystallizes in the isometric system, theoretically forming cubic or octahedral crystals. In nature, however, well-formed crystals are almost never observed. It occurs as irregular grains, fine flakes, platelets, and scales, usually submillimeter in size.

Geological environment

## Genesis Native molybdenum is a mineral formed under strongly reducing conditions. Its main environments of formation are ultramafic igneous rocks (e.g., dunites, peridotites), where it occurs as fine grains. It is also found in some porphyry copper-molybdenum deposits and in skarns. It can be found in alluvial deposits (placers) as a heavy mineral, derived from the weathering of primary rocks. ## Mineral Associations It most often co-occurs with platinum group minerals, chromite, magnetite, ilmenite, as well as with molybdenite, pyrite, and chalcopyrite. In ultramafic rocks, it is accompanied by olivine and pyroxenes. ## Localities Confirmed occurrences of native molybdenum are few and scattered worldwide. The most important include the Koryak-Kamchatka massif in the Russian Far East (where relatively large grains have been found), the Allende meteorite in Mexico, and some deposits in Canada (Quebec) and the USA. Occurrences are mainly microscopic.

Rarity

Very rare

For collectors

## Quality Criteria Due to its extreme rarity, every confirmed specimen of native molybdenum has scientific and collectible value. The most important criterion is the size of the grains – the larger and more visible, the more valuable the specimen. Specimens where molybdenum is visible to the naked eye or under slight magnification are most desirable. Well-documented locality and analytical confirmation of chemical composition are also important. ## Popular Localities Specimens from the Kamchatka Peninsula in Russia are most prized by micromineral collectors, as some of the largest known grains of native molybdenum originate from there.

Care and storage

## Cleaning Specimens of native molybdenum, usually in the form of fine grains embedded in the host rock, practically do not require cleaning. If necessary, a soft brush can be used to remove dust. Chemical or mechanical cleaning is not recommended. ## What to Avoid Avoid contact with strong acids and chemical reagents, which can react with the metal. Although stable, prolonged exposure to moist air can lead to slow tarnishing of the surface. It should not be heated. ## Storage Store in a dry place, preferably in a closed display case or box, to protect it from dust and contaminants. Due to its softness, avoid contact with harder minerals that could scratch it.