Aluminium

Chemical formula: Al

Native aluminum is an extremely rare native element, occurring in nature as small grains and flakes under specific geological conditions.

## Characteristics Native aluminum is a naturally occurring, pure form of the element aluminum. In nature, it most often forms small, irregular grains, flakes, or scales, typically not exceeding a few millimeters in size. Microscopic, well-formed crystals are observed very rarely. It has a characteristic metallic luster and a silvery-white or tin-white color, which can tarnish in air due to the formation of a thin oxide layer. ## Physical Properties This mineral is very soft and light, and its density is almost identical to that of industrially produced aluminum. It is highly malleable and ductile, meaning it can be easily shaped and stretched under pressure. The luster is strongly metallic, and the mineral itself is completely opaque. ## Colors and Varieties Native aluminum does not form color varieties. Its color is constant, silvery-white, sometimes with a tin-white tint. The surface can be covered with a dull, gray oxide coating. ## History and Name The name of the element, from which the mineral's name is derived, was proposed by Humphry Davy in 1812 and comes from the Latin word "alumen," meaning alum. The existence of native aluminum was long questioned. It was finally confirmed and recognized as a mineral by the International Mineralogical Association (IMA) in 1978, after its identification in volcanic exhalation products at Tolbachik volcano in Kamchatka, Russia. ## Applications Due to its extreme rarity, native aluminum has no industrial applications. It is solely an object of scientific and collecting interest. The entire global demand for this metal is met by metallurgical production from bauxite ores.

Properties

Mohs hardness: 1.5
Luster: Metallic
Streak: White
Density: 2.7
Cleavage: None
Fracture: Hackly
Transparency: Opaque
Crystal system: Isometric

Diagnostic features

## Identification Key diagnostic features of native aluminum are its tin-white color, strong metallic luster, very low hardness, and exceptionally low density – specimens are unnaturally light compared to other native metals. The mineral is also malleable. ## Distinguishing from similar minerals Native aluminum can be confused with native silver or native platinum. Silver is much denser and over time develops a dark, black sulfide tarnish. Platinum is also much denser and harder. Final differentiation often requires density tests or chemical analysis. ## Crystal Forms It most often occurs as irregular grains, flakes, scales, and small nuggets. Crystals, observed extremely rarely, take the form of cubes and octahedra, but are usually microscopic in size.

Geological environment

## Genesis Native aluminum forms under unique, strongly reducing geological conditions where free oxygen is absent. Its main environments of formation are volcanic exhalation zones (fumaroles), where hot gases reduce aluminum compounds from surrounding rocks. It also occurs in some ultramafic intrusions, serpentinites, and as a product of lightning strikes on rocks (fulgurites). ## Mineral Associations At the type locality (Tolbachik volcano), it co-occurs with other native elements (iron, silicon), troilite, hematite, and a number of rare volcanic minerals. In other locations, it is found in association with moissanite, corundum, graphite, and pyrite. ## Localities The most important and well-known worldwide locality for native aluminum is Tolbachik volcano on the Kamchatka Peninsula in Russia. Confirmed occurrences have also been reported in ophiolite complexes in Azerbaijan and China, as well as in Bulgaria and several other places around the world.

Rarity

Very rare

For collectors

## Quality Criteria The most important factor influencing collectible value is reliable documentation of the specimen's natural origin from a specific, known locality. Extremely rare, microscopic crystals with regular shapes are highly prized. The size of grains or flakes also matters. Co-occurrence with other rare minerals enhances value. ## Popular Localities Specimens from Tolbachik volcano in Russia are by far the most valued and sought after by collectors. This locality has provided the best-studied and described samples of this mineral.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush and distilled water or alcohol. Due to its low hardness, the mineral is susceptible to scratches. Ultrasonic cleaners are not recommended. ## What to avoid Avoid contact with acids and strong bases, which can react with the metal. Although a protective oxide layer forms on the surface, prolonged exposure to moisture can lead to slow changes. Protect from mechanical damage and scratching. ## Storage It is recommended to store specimens in a dry place, preferably in closed display boxes or showcases, to protect them from dust, moisture, and physical damage.