Lindbergite

Chemical formula: Mn<sup>2+</sup>(C<sub>2</sub>)<sup>6+</sup>O<sub>4</sub>·2H<sub>2</sub>O

Lindbergite is a hydrated manganese oxalate, forming aggregates of small, prismatic crystals with a color ranging from yellow to reddish-brown.

## Characteristics Lindbergite is a hydrated manganese oxalate belonging to the humboldtine group. It rarely forms well-developed, single crystals, occurring most often as radial or fibrous aggregates, rosette-like clusters, and crusts. Individual crystals are usually small, prismatic, or acicular. It is a secondary mineral, formed as a result of low-temperature hydrothermal processes or weathering. ## Physical Properties This mineral is characterized by relatively low hardness, measuring 2.5 on the Mohs scale. Its density ranges from 2.39 to 2.41 g/cm³. It exhibits a vitreous luster. It is transparent to translucent. ## Colors and Varieties Lindbergite ranges in color from pale yellow, through yellowish-brown, to reddish-brown. No named varieties are distinguished. ## History and Name The mineral is named in honor of Marie Louise Lindberg-Smith (1918-2005), an American mineralogist with the United States Geological Survey, in recognition of her contributions to the study of phosphate minerals. The mineral was described and approved by the IMA in 1986. ## Uses Due to its rarity and small crystal size, lindbergite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals.

Properties

Mohs hardness
2.5
Luster
Vitreous
Streak
Pale yellow
Density
2.39-2.41
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Lindbergite can be recognized by its characteristic, radial or fibrous aggregates of yellowish to reddish-brown color. Low hardness (2.5 on the Mohs scale) and vitreous luster are also important features. It often occurs in paragenesis with other manganese minerals in oxidation zones. ## Distinguishing from Similar Minerals It can be confused with other secondary manganese minerals of similar appearance, such as rhodochrosite or kutnohorite, but it differs significantly from them by its much lower hardness. From humboldtine (iron oxalate), it is distinguished by its chemical composition (presence of manganese instead of iron) and often a slightly different color. Accurate identification requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD). ## Crystal Forms Lindbergite crystals are monoclinic, with prismatic or acicular habit. They are usually very small and form aggregates: radial, fibrous, spherulitic (spherical), or rosette-like. It also occurs as crusts and veins.

Geological environment

## Genesis Lindbergite is a secondary mineral. It forms under low-temperature hydrothermal conditions, often in the late stages of crystallization in granitic pegmatites. It also forms in the oxidation zones of manganese deposits, as a product of weathering of other manganese minerals, especially rhodochrosite. ## Mineral Associations This mineral co-occurs with other manganese minerals and phosphates. The most common associated minerals are rhodochrosite, strengite, hureaulite, taranakite, as well as quartz and pyrite. ## Localities The most important and classic localities for lindbergite are in Brazil, in the state of Minas Gerais (Sapucaia, Cigana mines, and especially in the Galileia region). It is also known from the Tip Top mine in Custer County, South Dakota (USA), and from Hagendorf-Süd in Bavaria (Germany).

Rarity

Rare

For collectors

## Quality Criteria The most valued specimens by collectors are those with well-formed, radial aggregates of intense, yellowish-brown or reddish-brown color. Aesthetic composition with associated minerals is also important, e.g., a contrasting combination with white quartz or purple strengite. Due to the small size of the crystals, specimens with visible, distinct crystalline structures are particularly sought after. ## Popular Localities The most famous localities, yielding the best quality lindbergite specimens, come from the pegmatites in the Galileia region of Minas Gerais, Brazil. Specimens from these localities are considered the global standard for this mineral.

Care and storage

## Cleaning Lindbergite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its low hardness and potential solubility, contact with water, especially hot water and acids, should be avoided. If liquid is necessary, the specimen can be carefully wiped with a cloth minimally moistened with alcohol, ensuring quick evaporation. ## What to Avoid Ultrasonic cleaners, chemical agents, acids, and bases should be avoided. The mineral is sensitive to high temperatures, which can lead to dehydration and destruction of its structure. It should be protected from prolonged exposure to direct sunlight, which can cause fading. ## Storage Lindbergite is a brittle and soft mineral, so it should be stored in a separate, padded box, away from harder minerals that could scratch it. It is best stored in stable conditions, away from sources of heat and moisture.

Sources

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