Mapiquiroite

Chemical formula: (Sr,Pb²⁺)(U⁴⁺,Y)Fe³⁺₂(Ti⁴⁺,Fe³⁺)₁₈O₃₈

Mapiqwiroite is a rare oxide mineral from the crichtonite group, characterized by its black color, metallic luster, and high density.

## Characteristics Mapiqwiroite is a very rare mineral belonging to the crichtonite group. It forms small, tabular or prismatic crystals with a hexagonal outline, usually not exceeding 1 mm. Most often, it occurs as inclusions in other minerals. It is opaque, black in color, and has a metallic luster. ## Physical Properties This mineral is characterized by high hardness, estimated at 7 on the Mohs scale, and significant density of approximately 5 g/cm³. It has a black streak and metallic luster. It is brittle and exhibits an uneven fracture. ## History and Name The mineral's name comes from its discovery location in 1982 – the Mapiquiro uranium mine in Colombia, Tolima department. It was described by M. Deliens and P. Piret.

Properties

Mohs hardness
6
Color
Black
Luster
Metallic
Streak
Black
Density
4.670
Cleavage
None
Fracture
Uneven
Transparency
Opaque
Crystal system
Trigonal

Diagnostic features

## Identification Identification of mapiqwiroite is difficult without advanced research methods. It can be preliminarily recognized by its black color, metallic luster, high hardness, and co-occurrence with uraninite. Final confirmation requires chemical (EDS) and X-ray (XRD) analysis. ## Distinguishing from Similar Minerals It can be confused with other black, metallic minerals from the crichtonite group, such as crichtonite, senaite, or davidite. Differentiation is practically only possible based on chemical composition, especially the unique combination of strontium, uranium, and lead. ## Crystal Forms It forms small, hexagonal, tabular crystals, often with a prismatic habit. It typically occurs as single, isolated crystals or small clusters of inclusions.

Geological environment

## Genesis Mapiqwiroite forms in hydrothermal calcite veins cutting volcanic rocks (andesites). It is a secondary mineral, crystallizing in the late stage of hydrothermal processes. ## Mineral Associations It co-occurs with minerals such as uraninite, quartz, calcite, pyrite, chalcopyrite, galena, hematite, and senaite. ## Localities The only confirmed locality of this mineral in the world is its type locality – the Mapiquiro uranium mine, located approximately 30 km northeast of the city of Armero in the Tolima department, Colombia.

Rarity

Extremely rare

For collectors

## Quality Criteria As an extremely rare mineral, every mapiqwiroite specimen is valuable to specialized collectors. The most desirable are well-formed, standalone crystals with a distinct hexagonal outline, set on a contrasting matrix (e.g., white calcite). Crystal size is a key factor, and specimens exceeding 1 mm are exceptionally rare and valuable. ## Popular Localities The only source of specimens is the type locality in Colombia. Material from this location is practically unavailable on the collector's market.

Care and storage

## Cleaning Due to the rarity and small size of its crystals, mapiqwiroite specimens rarely require cleaning. If necessary, only use compressed air to remove dust. Avoid contact with water and chemical agents. ## What to Avoid The mineral is potentially radioactive due to its uranium content, so direct contact should be limited, and it should be stored away from other radiation-sensitive minerals. Avoid ultrasonics, high temperatures, and all chemicals. ## Storage Specimens should be stored under stable conditions, in sealed containers or display cases, away from sunlight and moisture. It is recommended to store them in a separate section of the collection due to potential radioactivity.

External references

Sources

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