Krinovite
Chemical formula: Na<sub>4</sub>(Mg<sub>8</sub>Cr<sup>3+</sup><sub>4</sub>)O<sub>4</sub>[Si<sub>12</sub>O<sub>36</sub>]
Krinovite is an extremely rare, emerald-green silicate found exclusively as microscopic grains in iron meteorites.
Description
## Characteristics Krinovite is a complex sodium, magnesium, and chromium silicate, belonging to the rare meteoritic minerals. It occurs as very small, usually not exceeding 0.2 mm, anhedral grains or small, lath-like crystals. Its most characteristic feature is an intense, emerald-green color, which makes it stand out against the metallic matrix of the meteorite. ## Physical Properties This mineral is characterized by a hardness of about 6 on the Mohs scale and a density of 3.36 g/cm³. It has a vitreous luster and is transparent. The presence of chromium in its structure is responsible for its vivid green color. ## Colors and Varieties Krinovite occurs exclusively in shades of green, from light green to deep, emerald green. No color varieties or commercial forms are known. ## History and Name The mineral was first described in 1966. Its name commemorates Evgeny Leonidovich Krinov (1906-1984), a distinguished Russian meteorite researcher and long-time curator of the meteorite collection of the Russian Academy of Sciences. ## Applications Krinovite has no industrial applications. Its significance is purely scientific, as an indicator of conditions prevailing in the parent bodies of asteroids. It is also an object of interest for specialized meteorite collectors.
Diagnostic features
## Identification The key diagnostic feature of krinovite is its unique occurrence environment – exclusively in iron meteorites, most often in graphite-troilite nodules. Its intensely emerald-green color is very characteristic. However, definitive identification is only possible using advanced analytical methods, such as X-ray microanalysis (EDS/WDS). ## Distinguishing from Similar Minerals Krinovite is sometimes confused with kosmochlor (ureyite), another green silicate found in a similar environment. Kosmochlor also has a green color, but distinguishing between the two minerals based on visual characteristics is impossible and requires chemical composition analysis. ## Crystal Forms It forms microscopic, irregular grains or small, elongated, lath-like crystals, usually embedded in graphite, troilite, or at the boundary with the metallic background.
Geological environment
## Genesis Krinovite is a high-pressure mineral, crystallizing under specific conditions prevailing within the interiors of asteroids, from which IAB group iron meteorites originate. Its formation is associated with metamorphic processes or crystallization from a silicate melt trapped in metal. ## Mineral Associations It most often co-occurs with minerals typical of inclusions in iron meteorites, such as graphite, troilite, daubréelite, chromite, kosmochlor, and with iron-nickel alloys (kamacite and taenite). ## Locations Its presence has been confirmed in several iron meteorites worldwide. The most important include the Canyon Diablo meteorite (Arizona, USA), which is the type locality, as well as Wichita County (Texas, USA) and Youndegin (Western Australia).
Rarity
Extremely rare
Collector aspects
## Quality Criteria Due to its extreme rarity and microscopic size, the primary criterion for value is the documented presence of krinovite in a meteorite specimen. Specimens in which krinovite grains are relatively large (on a micro scale), numerous, and form distinct clusters with intense color are more highly valued. The value of a specimen is inextricably linked to the value of the meteorite itself. ## Popular Localities The most known and best-studied specimens come from the type material, i.e., fragments of the Canyon Diablo meteorite found around Meteor Crater in Arizona.
Care and storage
## Cleaning Krinovite occurs as an inclusion in iron meteorites, so care applies to the entire specimen. Cleaning krinovite grains is neither possible nor advisable. Any attempts to clean a meteorite should be carried out by specialists to avoid damaging its surface and preventing corrosion. ## What to Avoid The greatest threat to specimens containing krinovite is moisture. It causes rusting of the surrounding iron-nickel alloy, which can lead to the destruction of the entire specimen. Contact with water and chemicals must be strictly avoided. ## Storage Meteorite specimens with krinovite must be stored in very dry conditions. It is recommended to keep them in sealed plastic containers (e.g., membrane boxes) along with a desiccant, such as silica gel.