Karwowskiite

Chemical formula: Ca₉Mg(Fe²⁺₀.₅◻₀.₅)(PO₄)₇

Karwowskiite is a newly discovered, extremely rare mineral from the merrillite group, occurring in the Morasko iron meteorite as microscopic grains.

## Characteristics Karwowskiite is a mineral from the merrillite group, approved as a new mineral species by the IMA in 2023. It occurs as very fine, anhedral (lacking crystal faces) grains up to 200 micrometers in size, but most often significantly smaller. It is intergrown with other phosphate minerals within the Morasko iron meteorite. Due to its microscopic size, its visual characteristics cannot be assessed with the naked eye. ## Physical Properties Due to its microscopic nature, most physical properties, such as hardness, density, luster, or transparency, have not been determined. Hardness is estimated at approximately 5 on the Mohs scale, and the calculated density based on the formula is 3.13 g/cm³. The mineral exhibits weak pleochroism from colorless to pale green. ## Colors and Varieties Observed in transmitted light, it is colorless to pale green. No varieties have been distinguished. ## History and Name The mineral's name honors Professor Łukasz Karwowski (1945-2022), a Polish geologist, mineralogist, and petrologist from the University of Silesia in Katowice, a researcher of the Morasko meteorite, and a discoverer of many new extraterrestrial minerals. The mineral was described by a research team consisting of Łukasz Kruszewski, Andrzej Muszyński, and Evgeny

Properties

Mohs hardness
4-0
Color
Colorless with a green tint
Luster
Vitreous
Streak
white
Density
3.085
Cleavage
None
Fracture
Conchoidal
Transparency
Transparent to translucent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of karwowskiite is possible only through advanced laboratory methods, such as X-ray microanalysis (EDS/WDS) in an electron microscope and X-ray diffraction (XRD). It is unrecognizable to the naked eye. In microscopic studies, it stands out as anhedral grains within other phosphates. ## Distinguishing from Similar Minerals It can be confused with other phosphates from the merrillite group, such as merrillite itself or whitlockite, which often co-occur with it. Final differentiation requires precise analysis of the chemical composition, particularly the proportions of calcium, magnesium, and iron. ## Crystal Forms Karwowskiite forms exclusively anhedral, i.e., irregular, grains with sizes not exceeding 200 micrometers. No well-formed crystals have been observed.

Geological environment

## Genesis Karwowskiite is a mineral of extraterrestrial origin. It formed as a result of shock metamorphism processes that occurred in the parent body of an asteroid or during the impact of a meteorite with Earth. It crystallized within phosphate aggregates inside the metallic mass of the iron meteorite. ## Mineral Associations This mineral occurs in close association with other phosphates, mainly merrillite, as well as with graphite, troilite, schreibersite, and other accessory minerals within the metallic matrix (kamacite, taenite) of the Morasko meteorite. ## Localities The only confirmed locality of karwowskiite in the world is the Morasko iron meteorite, found in the "Meteoryt Morasko" nature reserve in Poznań, Poland. This is the type locality for this mineral.

Rarity

Extremely rare

For collectors

## Quality Criteria From a collector's perspective, the value of a specimen does not lie in the visual characteristics of karwowskiite itself, which is invisible to the naked eye. The value lies in the fragment of the Morasko meteorite in which the presence of this mineral has been identified. Such specimens primarily have immense scientific value and are extremely valuable for specialized institutional and private collections that gather type minerals or rare extraterrestrial minerals. ## Popular Localities The only source of specimens is the Morasko Meteorite Reserve in Poland. Obtaining material from this area is strictly regulated and requires permits.

Care and storage

## Cleaning Due to the extreme rarity and microscopic size of the grains intergrown in the meteorite matrix, karwowskiite specimens are not subject to cleaning in the traditional sense. Any interventions can only be carried out under laboratory conditions by specialists. ## What to Avoid Any attempts to independently extract the mineral, use chemicals, ultrasonics, or mechanical cleaning should be avoided. Each such attempt risks irreversible destruction of this unique material. ## Storage Morasko meteorite specimens containing karwowskiite should be stored in stable conditions, away from moisture, dust, and extreme temperature changes, preferably in a specialized box or display case.

External references

Sources

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