Lithiophorite

Chemical formula: (Al,Li)Mn₄+O₂(OH)₂

Lithiophorite is a hydrated aluminum and manganese oxide with lithium, forming black, botryoidal or earthy aggregates with a metallic luster.

## Characteristics Lithiophorite is a relatively rare mineral from the oxide group, chemically classified as a hydrated aluminum, lithium, and manganese oxide. Its name refers to its chemical composition – the presence of lithium (Greek *lithion*) and its similarity to psilomelane (Greek *phoros* – bearer). It rarely forms discernible crystals, most often occurring as radial, reniform, botryoidal, or grape-like aggregates. It is also found in the form of earthy, compact aggregates, or as black, shiny coatings and crusts on other minerals. ## Physical properties This mineral is characterized by a hardness of about 3 on the Mohs scale, making it relatively soft. It has a distinct luster, described as metallic to submetallic, and in the case of earthy forms, dull. It is opaque. Its density ranges from 3.14 to 3.37 g/cm³. ## Colors and varieties Lithiophorite is a mineral of uniform color. It is usually bluish-black to black. No color varieties or commercial varieties are distinguished. ## History and name The name lithiophorite, given in 1870 by the German mineralogist August Breithaupt, comes from the Greek words *lithion* (lithium) and *phoros* (bearer), which directly refers to its chemical composition. This mineral was first described based on samples from a mine in the Schneeberg region in Saxony, Germany. ## Uses Due to its rarity and usually unstriking forms, lithiophorite has no significant industrial application. However, it is an object of interest for collectors specializing in rare and systematic minerals.

Properties

Mohs hardness: 3
Luster: Metallic to submetallic
Streak: Black with brownish tinge
Density: 3.14-3.37
Cleavage: Perfect on {0001}
Fracture: Uneven
Transparency: Opaque
Crystal system: Trigonal

Diagnostic features

## Identification Lithiophorite is most easily recognized by its characteristic black or bluish-black color, metallic luster, and typical forms of occurrence – reniform, grape-like (botryoidal), or radial aggregates. An important diagnostic feature is its black streak with a brownish tint and relatively low hardness (about 3 on the Mohs scale). ## Distinguishing from similar minerals Lithiophorite is often confused with other black manganese oxides, such as psilomelane, hollandite, cryptomelane, or pyrolusite. It differs from pyrolusite by its lower hardness (pyrolusite is very soft and stains fingers) and lack of a distinct fibrous structure. From cryptomelane and hollandite, which are harder, it is distinguished by a test for the presence of lithium and aluminum. Psilomelane (romanechite) is usually harder (5-6) and has a higher density. ## Crystal forms Well-formed crystals are extremely rare and appear as small, hexagonal plates. It is most commonly found in the form of compact, reniform, botryoidal, and also radially fibrous aggregates. It often forms thin coatings and crusts on rocks or other minerals.

Geological environment

## Genesis Lithiophorite is a secondary mineral, forming in the oxidation (weathering) zones of manganese ore deposits. It forms as a result of the weathering of other manganese and lithium-bearing minerals, such as spodumene or lepidolite, in an aluminum-rich environment. It can also crystallize in low-temperature hydrothermal veins. ## Mineral associations This mineral often co-occurs with other manganese oxides, such as pyrolusite, cryptomelane, hollandite, romanechite (psilomelane), and birnessite. Goethite, lepidocrocite, quartz, kaolinite, and various lithium minerals can also be found in its company. ## Localities Key global localities that yield well-formed specimens include Schneeberg in Saxony (Germany), where it was discovered, and the Postmasburg region in the Republic of South Africa. It also occurs in many places in the United States (e.g., Socorro County in New Mexico and the Black Hills region in South Dakota), Brazil (Minas Gerais state), and Australia (Broken Hill).

Rarity

Not very common

For collectors

## Quality criteria The most valued specimens by collectors are those of lithiophorite exhibiting well-formed botryoidal (grape-like) or reniform aggregates with a strong, metallic luster. The attractiveness is enhanced by the contrasting placement of black lithiophorite on a light rock matrix. Rare, microscopic crystals in the form of hexagonal plates are highly prized by systematic collectors. Earthy and dull specimens have significantly lower collector value. ## Popular localities The historical localities in Schneeberg, Germany, are considered classic and yield the best specimens. High-quality botryoidal specimens also come from the manganese fields in the Kuruman and Postmasburg regions of South Africa. American localities, such as those in New Mexico, also provide interesting collector specimens.

Care and storage

## Cleaning Lithiophorite specimens should be cleaned very carefully, preferably dry, using a soft brush to remove dust. If necessary, a damp cloth or cotton swab with distilled water can be used, but prolonged soaking should be avoided. Ultrasonic cleaners, which can damage delicate aggregates, should be avoided. ## What to avoid The mineral is sensitive to acids, which can damage it. It should be protected from contact with household and laboratory chemicals. As a relatively soft mineral, it is susceptible to scratches, so contact with harder minerals should be avoided. ## Storage Collector's specimens of lithiophorite, especially those in the form of delicate coatings or radial aggregates, are best stored in separate, padded boxes or display cases to prevent abrasion and mechanical damage. It is not sensitive to light, but extreme temperatures and humidity should be avoided.

Sources

IMA Mineral List (CNMNC)