Keplerite
Chemical formula: Ca<sub>9</sub>(Ca<sub>0.5</sub>☐<sub>0.5</sub>)Mg(PO<sub>4</sub>)<sub>7</sub>
Keplerite is a newly discovered phosphate mineral, named after the astronomer Johannes Kepler, distinguished by its unique crystal structure.
Properties
- Mohs hardness
- ~5
- Luster
- Vitreous
- Streak
- White
- Density
- 3.16
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of keplerite is possible only through advanced laboratory techniques. This requires the use of a scanning electron microscope (SEM) with chemical composition analysis (EDS) and electron backscatter diffraction (EBSD) or X-ray diffraction to confirm its unique crystal structure. Optically, in transmitted light, it is colorless and does not exhibit features that allow it to be distinguished from other fine-grained phosphates. ## Distinguishing from Similar Minerals Keplerite is closely related to other phosphates of the merrillite group, such as merrillite itself. Differentiation from them requires precise diffraction analysis, which reveals differences in symmetry and unit cell parameters. Merrillite crystallizes in the hexagonal system, while keplerite crystallizes in the trigonal system. ## Crystal Forms Keplerite forms exclusively anhedral (irregularly shaped) grains of microscopic size, occurring as inclusions in other minerals, mainly olivine and pyroxene.
Geological environment
## Genesis Keplerite is an extraterrestrial mineral. It forms under high temperature and pressure conditions during shock metamorphism processes within the parent bodies of asteroids, from which ordinary chondrites originate. Its presence is an indicator of intense impact events in the history of the parent body. ## Mineral Associations Minerals co-occurring with keplerite in meteorites are primarily olivine, pyroxene (both ortho- and clinopyroxene), plagioclase (in the form of maskelynite), chromite, troilite, kamacite, taenite, and other phosphates such as apatite and merrillite. ## Localities The only confirmed locality of keplerite (type locality) is the NWA 4734 meteorite. This is an ordinary chondrite (L3), found in 2006 in the Sahara in Northwest Africa. Its occurrence in other geochemically similar meteorites is possible, but requires further research.
Rarity
Extremely rare
For collectors
## Quality Criteria Keplerite, as a microscopic mineral, is not an object of collector trade in the form of isolated specimens. The collector and scientific value lies in the meteorite itself in which it was identified. For research institutions and specialized meteorite collectors, the value of a specimen is enhanced by the documented presence of rare minerals such as keplerite. ## Market Prices Not applicable. The price refers to the entire meteorite specimen, not to the mineral itself. ## Popular Localities The only known "locality" is the NWA 4734 meteorite.
Care and storage
## Cleaning Due to its microscopic size and occurrence as inclusions in other minerals, keplerite specimens are not subject to cleaning in the collector's sense. Any research preparations (thin sections, polished sections) require specialized laboratory equipment. ## What to Avoid Contact with strong acids, which can etch phosphates, should be avoided. Research preparations should be protected from mechanical damage and contamination. ## Storage Meteorite specimens containing keplerite should be stored under stable conditions, away from moisture and chemical contaminants, preferably in specialized meteorite storage containers. Microscopic preparations should be stored in dedicated boxes.