Perryite
Chemical formula: (Ni,Fe)<sub>8</sub>(Si,P)<sub>3</sub>
Perryite is an extremely rare nickel iron silicide, found almost exclusively in meteorites.
Properties
- Mohs hardness
- 6
- Luster
- Metallic
- Streak
- Black
- Density
- 7.7
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of perryite is impossible without advanced laboratory techniques. In polished meteorite sections, it can be observed under a microscope as small, bright grains with a metallic luster. Definitive identification requires chemical composition analysis (EDS) and X-ray diffraction (XRD) studies. ## Distinguishing from Similar Minerals Under a microscope, perryite can be confused with other rare meteoritic minerals, such as schreibersite ((Fe,Ni)₃P) or cohenite ((Fe,Ni,Co)₃C). Differentiation is based on precise chemical composition analysis, particularly the detection of silicon, which is a key component of perryite. ## Crystal Forms Perryite forms exclusively anhedral (irregular) grains of microscopic size, usually below 0.1 mm. It occurs as inclusions in other mineral phases of the meteorite, mainly in kamacite and taenite.
Geological environment
## Genesis Perryite is a mineral of extraterrestrial origin. It forms under strongly reducing conditions, with very low oxygen fugacity, which prevailed in the early Solar System during the formation of planetesimals. It crystallizes from the metallic phase within the parent bodies of some meteorites, mainly enstatite chondrites and some iron meteorites (e.g., from the IAB group). ## Mineral Associations This mineral co-occurs with other minerals typical of meteorites. Its most common associates are kamacite, taenite (iron-nickel alloys), schreibersite, troilite, enstatite, daubréelite, and oldhamite. ## Localities Confirmed occurrences of perryite are limited to a dozen or so meteorites. The most important include the Horse Creek iron meteorite (Colorado, USA - discovery site), enstatite chondrites such as Abee (Alberta, Canada), Saint-Sauveur (France), Qingzhen (China), and some inclusions in iron meteorites, e.g., in the Mundrabilla meteorite (Australia).
Rarity
Extremely rare
For collectors
## Quality Criteria The collector's value of perryite is inextricably linked to the value of the meteorite in which it is found. Since the mineral is microscopic, it is not evaluated based on form or color. The most valuable specimens come from rare, well-studied, and classified meteorites. For scientific institutions and specialized collectors, the ability to observe perryite in a metallographic section along with its associated minerals is crucial. ## Popular Localities Meteorite specimens containing perryite from classic localities such as Horse Creek or Abee are extremely valuable and practically unavailable on the commercial market. Most of the material is held in institutional and museum collections.
Care and storage
## Cleaning Specimens (most often meteorite fragments) containing perryite should be cleaned with utmost care. The safest method is to use compressed air to remove loose dust. Any "wet" methods are discouraged due to the risk of corrosion of associated metallic minerals. ## What to Avoid Contact with water, chemicals, and especially acids, which can damage both perryite and the surrounding meteorite material, must be strictly avoided. The mineral is sensitive to moisture, which accelerates oxidation and corrosion, so maintaining it in a dry environment is crucial. ## Storage Storing specimens with perryite requires an environment with controlled, low humidity. It is recommended to use sealed containers (so-called "membrane boxes") or display cases with moisture absorbers (e.g., silica gel). Avoid sudden temperature changes.