Panethite
Chemical formula: (Na,Ca,K)<sub>1-x</sub>(Mg,Fe<sup>2+</sup>,Mn<sup>2+</sup>)PO<sub>4</sub>
Panethite is an extremely rare sodium, calcium, magnesium, and iron phosphate, found exclusively in chondritic meteorites.
Properties
- Mohs hardness
- 3.5
- Luster
- Vitreous
- Streak
- White
- Density
- 3.02
- Cleavage
- Good on {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of panethite is impossible without advanced laboratory techniques, such as electron microprobe (EDS/WDS) or X-ray diffraction (XRD). Within a meteorite, it can be suspected based on its yellowish or greenish coloration, vitreous luster, and co-occurrence with other phosphates. ## Distinguishing from Similar Minerals It can be confused with other meteoritic phosphates, such as stanfieldite, farringtonite, or whitlockite (merrillite). Differentiation requires chemical analysis, especially of sodium, calcium, and magnesium content. ## Crystal Forms Panethite forms small, rounded or irregular grains, usually without visible crystal faces (anhedral).
Geological environment
## Genesis Panethite is a primary mineral, crystallizing under specific conditions prevalent during the formation or metamorphism of chondrite parent bodies. It forms in a silica-poor environment, in the presence of other phosphates and iron-nickel alloys. ## Mineral Associations It most often co-occurs with other phosphates found in meteorites, such as whitlockite (merrillite), stanfieldite, brianite, and farringtonite. It is also accompanied by the main components of chondrites: olivine, pyroxene, plagioclase, and metallic minerals - kamacite and taenite. ## Localities Its occurrence has been confirmed exclusively in stony meteorites. In addition to the type locality (Dayton meteorite, Ohio, USA), it has also been identified in the El Sampal (Argentina), Zag (Morocco) meteorites, and several other chondrites and ureilites.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a specimen with panethite is identical to the quality of the meteorite itself in which it is found. For scientific and collecting purposes, the most valuable are thin sections of meteorites, on which individual mineral grains can be identified and observed under a microscope. The identification of panethite in such a specimen significantly increases its scientific value. ## Popular Localities Since it is a meteoritic mineral, there are no "localities" in the traditional sense. Specimens come from the fall or discovery sites of meteorites where it was identified, e.g., from the vicinity of Dayton in the USA or the El Sampal region in Argentina.
Care and storage
## Cleaning Specimens containing panethite (usually meteorite fragments) should not be wet-cleaned. A soft brush or compressed air from a safe distance can be used to remove dust. ## What to Avoid Avoid contact with water, chemicals, acids, and detergents. As a phosphate mineral, it may react with acids. It should also be protected from moisture, which can cause corrosion of co-occurring metallic minerals (e.g., kamacite) and lead to the degradation of the entire specimen. ## Storage Meteorite fragments with panethite should be stored in dry conditions, preferably in an airtight container (e.g., a membrane box) with a desiccant (e.g., silica gel). Avoiding sudden temperature changes is recommended.