Magnesiochangesite-(Y)

Chemical formula: (Ca₈Y)&#₉₇₄₄;Mg(PO₄)₇

Magnesiochangesite-(Y) is an extremely rare phosphate from the cerite supergroup, discovered in lunar soil samples returned by the Chang'e 5 mission.

## Characteristics Magnesiochangesite-(Y) is a phosphate mineral that is the magnesium equivalent of changesite-(Y). It belongs to the cerite supergroup. It occurs as microscopic grains in lunar regolith and basalts. Due to the submillimeter size of the crystals, its visual features are impossible to observe with the naked eye. ## Physical properties This mineral was identified based on advanced microscopic studies and X-ray diffraction. Most macroscopic physical properties, such as hardness, fracture, or cleavage, remain undetermined due to the microscopic size of the available samples. ## Colors and varieties It occurs as microscopic, colorless crystals. It has no known varieties. ## History and name The name of the mineral refers to its chemical composition, which is dominated by magnesium, and its direct relationship to the previously described changesite-(Y). It was discovered in lunar soil samples collected in the Statio Tianchuan area in Oceanus Procellarum (Ocean of Storms) by the Chinese probe Chang'e 5.

Properties

Crystal system: Trigonal

Diagnostic features

## Identification Identification is possible only through advanced analytical methods, such as electron microscopy, Raman spectroscopy, and X-ray diffraction (XRD). ## Distinguishing from similar minerals It must be distinguished from other lunar phosphates, in particular from changesite-(Y), which contains iron instead of magnesium, and from merrillite. The distinction is based on precise analysis of chemical composition using an electron microprobe. ## Crystal forms It forms microscopic crystals that crystallize in the trigonal system. They usually occur in the spaces between grains of other rock-forming minerals.

Geological environment

## Genesis The mineral crystallizes under specific extraterrestrial conditions, in cooling basaltic melts on the surface of the Moon, in an environment completely devoid of water and oxygen. ## Mineral associations It co-occurs with typical lunar rock minerals, such as pyroxenes, plagioclase, ilmenite, troilite, and other phosphates, including apatite. ## Localities The only known and confirmed locality is Statio Tianchuan in Oceanus Procellarum (Ocean of Storms) on the Moon, which was the landing site of the Chang'e 5 mission.

Rarity

Extremely rare

For collectors

## Quality criteria The mineral has exclusively scientific and research significance. Due to its origin and microscopic size, it is not evaluated for visual appeal. ## Popular localities All known samples originate from the Moon and are state property, which is why this mineral does not occur on the collector market.

Care and storage

## Cleaning Specimens of this mineral are not available in private collections. Lunar samples are studied exclusively under sterile laboratory conditions, which rules out standard cleaning methods. ## What to avoid Terrestrial contamination, moisture, and an oxygen atmosphere should be avoided, as they could affect the original chemical and physical state of the lunar samples. ## Storage Samples containing this mineral are stored in specialized state research laboratories under high vacuum conditions or in an inert gas atmosphere (e.g., nitrogen).

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External references

https://www.mindat.org/min-499614.html