Meurigite-K

Chemical formula: [K(H₂O)₂.₅][Fe³⁺₈(PO₄)₆(OH)₇]·4H₂O

Meurigite-K is a rare iron and potassium phosphate, forming characteristic, silky aggregates of yellowish color.

## Characteristics Meurigite-K is a hydrated iron and potassium phosphate, belonging to the meurigite group. It occurs as spherical or hemispherical aggregates and radial clusters of small, acicular or fibrous crystals. Individual crystals are usually too small to be seen with the naked eye, and clusters rarely exceed a few millimeters in diameter. ## Physical Properties This mineral is characterized by a silky luster, resulting from its fibrous structure. It is translucent and relatively soft, with a hardness of 3 on the Mohs scale. Its density is approximately 2.96 g/cm³. ## Colors and Varieties Meurigite-K ranges in color from pale yellow and canary yellow to yellowish-brown. Cream and white specimens are also found. No named varieties are distinguished. ## History and Name The mineral was formally described in 1995. Its name refers to its chemical composition – it is an analog of meurigite with dominant potassium (K) – and honors the Welsh mineral collector, John Meurig Thomas (1926–1991). The type locality where this mineral was first identified is the Chino Mine (Santa Rita) in Grant County, New Mexico, USA. ## Uses Meurigite-K has no industrial application and is solely a mineral of scientific and collecting interest.

Properties

Mohs hardness
3
Luster
Silky
Streak
White
Density
2.96
Cleavage
{001}
Fracture
None observed
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Meurigite-K can be identified by its characteristic, radial or spherical aggregates with a silky luster and yellowish color. It forms crusts on other minerals in the oxidation zones of ore deposits. ## Distinguishing from Similar Minerals It can be confused with other secondary phosphates of similar appearance, such as cacoxenite, strengite, or variscite. Differentiation often requires chemical analysis (EDS) to confirm the presence of potassium and iron. Compared to cacoxenite, meurigite-K forms more compact, spherical aggregates. ## Crystal Forms It forms small, acicular or bladed crystals that combine into radial, spherical, or hemispherical aggregates. It rarely occurs as single, well-formed crystals.

Geological environment

## Genesis This is a secondary mineral, formed in the oxidation zones (gossans) of ore deposits, as a result of the weathering of primary phosphorus-bearing minerals (e.g., apatite) in the presence of iron minerals. ## Mineral Associations It often co-occurs with other secondary minerals, such as goethite, hematite, jarosite, strengite, leucophosphite, and also with quartz. ## Localities The most important and classic locality for this mineral is the Chino Mine in New Mexico, USA. It is also known from several other locations worldwide, including the Willard Mine in Pershing County, Nevada, USA, and from Germany (Hesse).

Rarity

Rare

For collectors

## Quality Criteria The most valued specimens by collectors are those with well-formed, spherical aggregates of intense, canary-yellow color, contrasting with the dark host rock (matrix). The absence of damage to the delicate, fibrous structures is also important. ## Popular Localities Specimens from the type locality, the Chino Mine in New Mexico, are most sought after due to their historical significance.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to its fragility and possible reactivity, contact with water, and especially with chemicals, should be avoided. ## What to Avoid Avoid ultrasonic cleaners, chemical agents, acids, and detergents. The mineral is brittle and sensitive to shocks and abrasion. It should be protected from moisture and sudden temperature changes. ## Storage It is recommended to store specimens in closed, stable containers or display cases, away from dust and direct sunlight. It is best to keep it in its original collector's box to avoid mechanical damage to the delicate, fibrous aggregates.

External references

Sources

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