Paqueite

Chemical formula: Ca₃Ti₄+Si₂(Al,Ti₄+,Si)₃O₁₄

Paqueite is a newly discovered mineral from the apatite group, found as an inclusion in the Allende meteorite, distinguished by its unique chemical composition.

## Characteristics Paqueite is a mineral identified as microscopic inclusions in the Allende meteorite, which fell in Mexico in 1969. It occurs as single, isolated, irregularly shaped grains, reaching sizes up to 1.5 x 3.5 micrometers. Due to the extremely small size of the crystals, its visual characteristics cannot be assessed with the naked eye. ## Physical Properties Due to the microscopic size of the grains, most physical properties, such as hardness, luster, transparency, or density, have not been experimentally determined. Density was calculated based on the chemical formula and unit cell parameters, and is 3.65 g/cm³. ## Colors and Varieties The color and pleochroism of the mineral have not been determined due to the excessively small size of the grains. No varieties are known. ## History and Name The mineral was officially approved by the International Mineralogical Association (IMA) in 2013 under number 2013-097. The name honors Prof. Julie M. Paque, a researcher at the California Institute of Technology, for her contributions to meteorite mineral research. Paqueite was discovered by Chi Ma during the analysis of inclusions in the Allende meteorite. ## Uses Paqueite has no commercial or industrial applications. Its significance is purely scientific, serving as an indicator of processes occurring in the early Solar System.

Properties

Density: 3.65
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of paqueite is possible only using advanced analytical techniques, such as scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to determine its chemical composition. Its unique chemical composition is a key diagnostic feature. ## Differentiation from Similar Minerals Paqueite differs from other titanium minerals and silicates found in meteorites, such as perovskite, grossmanite, or kangite, by its unique chemical formula and crystal structure. Final differentiation requires electron backscatter diffraction (EBSD) analysis. ## Crystal Forms Paqueite has been found exclusively in the form of anhedral (irregular) grains of microscopic size.

Geological environment

## Genesis Paqueite is a mineral of extraterrestrial origin. It formed under conditions of high temperature and low pressure in the early Solar System. It crystallized from a gas or melt rich in calcium, aluminum, and titanium. It occurs in calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondrites, such as the Allende meteorite. ## Mineral Associations This mineral coexists with other minerals typical of CAIs, such as spinel, melilite, perovskite, hibonite, and anorthite. ## Localities The only confirmed locality of paqueite in the world is the Allende meteorite, which fell in the state of Chihuahua, Mexico.

Rarity

Extremely rare

For collectors

## Quality Criteria Paqueite does not occur in the form of collector's specimens. Its value is purely scientific. For research institutions and museums, fragments of the Allende meteorite in which the presence of this mineral has been identified are valuable. The quality of such a specimen is determined by its mineralogical context and the quality of analyses confirming the presence of paqueite. ## Popular Localities The only source of specimens in which paqueite can be identified is material from the Allende meteorite fall in Mexico.

Care and storage

## Cleaning Due to its occurrence as microscopic inclusions within the meteoritic rock, individual paqueite grains are not subject to cleaning. ## What to Avoid Allende meteorite specimens containing paqueite should be protected from moisture, chemicals, and extreme temperatures to prevent degradation of the entire sample. ## Storage Samples containing paqueite should be stored under stable conditions, preferably in a dry environment, in specialized meteorite storage containers, away from direct sunlight and contaminants.

Sources

IMA Mineral List (CNMNC)