Mammothite

Chemical formula: Pb²⁺₆Cu²⁺₄AlSb⁵⁺O₂(S⁶⁺O₄)₂Cl₄(OH)₁₆

Mammothite is a rare, sky-blue secondary sulfate mineral, discovered in the Mammoth mine in Arizona.

## Characteristics Mammothite is a complex sulfate of lead, copper, aluminum, and antimony. It occurs as small, prismatic or acicular crystals, rarely exceeding a few millimeters in length. Crystals often form radial aggregates, rosettes, or tangled masses on the surface of the host rock. Its most distinctive feature is its intense, sky-blue color. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 3. The crystals exhibit transparency and a vitreous luster. It is a brittle mineral, with an irregular, uneven fracture. It also possesses distinct cleavage in one direction. ## Colors and Varieties Mammothite occurs in shades ranging from cerulean blue through bluish-green to light blue. No named varieties are distinguished, and color variations depend on slight fluctuations in chemical composition. ## History and Name The mineral's name comes from its original locality – the Mammoth-Saint Anthony mine in Pinal County, Arizona (USA), where it was discovered. It was described and recognized as a new mineral species in 1983. Interestingly, it has two co-type localities: the aforementioned mine in Arizona and a site with metallurgical slags in Lavreotiki, Greece, where its presence was also identified at the same time. ## Uses Due to its rarity and small crystal size, mammothite has no industrial applications. It is solely an object of interest for collectors of rare minerals and scientists.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Pale blue
Density: 0
Cleavage: Distinct on {010}
Fracture: Irregular/Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Key diagnostic features include its characteristic sky-blue color, occurrence as small, acicular or prismatic crystals forming radial aggregates, and association with other secondary lead and copper minerals in oxidation zones. A light blue streak is also a helpful indicator. ## Distinguishing from Similar Minerals Mammothite can be confused with other blue secondary minerals, such as linarite, cyanotrichite, or aurichalcite. It differs from linarite by its lighter shade and crystal habit. From cyanotrichite and aurichalcite, which form similar acicular aggregates, it is often distinguished by a more prismatic crystal habit and a specific chemical environment (presence of antimony). ## Crystal Forms Mammothite forms elongated, prismatic crystals, often with a bladed cross-section. It is most commonly found in the form of radial aggregates, rosettes, and tangled, felted masses of fine needles.

Geological environment

## Genesis Mammothite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic deposits rich in lead and copper. It crystallizes as a result of complex weathering processes of primary ore minerals in the presence of solutions containing sulfates, chlorides, aluminum, and antimony. It is also found as a product of processes occurring in old, ancient metallurgical slags, as in the case of the Greek locality. ## Mineral Associations This mineral often co-occurs with other rare secondary minerals. At its type locality in Arizona, it was found in association with anglesite, cerussite, dioptase, wulfenite, phosgenite, boleite, and linarite. In Greece, it is accompanied by laurionite and paralaurionite. ## Localities The most important and also type localities are the Mammoth-Saint Anthony mine in Arizona (USA) and ancient slags in Lavreotiki, Greece. Besides these places, its occurrence has been reported in several other locations worldwide, including mines in Australia (Broken Hill), Germany (Badenweiler), and the United Kingdom (Cumbria), but these are very rare finds.

Rarity

Very rare

For collectors

## Quality Criteria The most desirable specimens for collectors are those with well-formed, clearly visible crystals of intense, sky-blue color. Rich aggregates of radial formations on a contrasting rock matrix are highly valued. Due to the small size of the crystals, specimens with needles or prisms a few millimeters long are considered exceptional. The purity of the specimen and the absence of damage to delicate crystals are crucial for its value. ## Popular Localities By far the most prized and commonly found on the collector's market are specimens from the type locality – the Mammoth-Saint Anthony mine in Tiger, Arizona. Specimens from this location have set the standard of quality for this mineral.

Care and storage

## Cleaning Mammothite specimens should be cleaned very carefully. It is best to use a soft brush to remove dust. If wet cleaning is necessary, use only distilled water and immediately and gently dry the specimen, for example, with compressed air from a safe distance. Avoid ultrasonic cleaners. ## What to Avoid Avoid contact with all chemicals, acids, and detergents. The mineral is sensitive to temperature changes and should not be exposed to direct sunlight, which can cause it to fade. As a lead-containing mineral, avoid inhaling dust and wash hands after handling the specimen. ## Storage Mammothite specimens, being brittle and often occurring as delicate needles, should be stored in separate, padded display boxes to prevent mechanical damage. Protect from dust and moisture.