Goryainovite

Chemical formula: Ca<sub>2</sub>(PO<sub>4</sub>)Cl

Goryainovite is a rare calcium phosphate chloride, forming colorless, granular aggregates in ultramafic rocks.

## Characteristics Goryainovite is a phosphate mineral that typically occurs as anhedral (lacking crystal faces) grains up to 0.3 mm in size. These grains form aggregates or occur as inclusions in other minerals, mainly in apatite. It is colorless and transparent, with a vitreous luster. It does not exhibit pleochroism or luminescence under ultraviolet light. ## Physical Properties The mineral has a hardness of 5 on the Mohs scale. Its density, calculated from the chemical formula and unit cell parameters, is 3.11 g/cm³. It possesses indistinct cleavage and an uneven fracture. ## History and Name The mineral is named in honor of Pavel Mikhailovich Goryainov (1934–2018), a Russian geologist and specialist in Precambrian geology and ore deposits, who worked at the Geological Institute of the Kola Science Centre of the Russian Academy of Sciences on the Kola Peninsula. Goryainovite was approved as a new mineral by the International Mineralogical Association (IMA) in 2019 (IMA2019-061).

Properties

Mohs hardness
5
Luster
Vitreous
Streak
White
Density
3.11
Cleavage
Indistinct
Fracture
Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identifying goryainovite is extremely difficult without advanced analytical methods. It requires chemical analysis (e.g., using an electron microprobe) to confirm its composition (presence of calcium, phosphorus, and chlorine) and structural analysis (X-ray diffraction). Visually, it is practically indistinguishable from many other colorless, granular minerals. ## Distinguishing from similar minerals The most similar mineral is apatite, in which goryainovite often occurs as inclusions. Differentiation is mainly possible based on chemical analysis – goryainovite is a phosphate chloride, while apatite is typically a fluoro- or hydroxyl-phosphate. Other colorless inclusion minerals require similar, detailed analysis. ## Crystal forms This mineral forms irregular, anhedral grains, usually less than 0.3 mm in size. It occurs as granular aggregates or as individual inclusions in other minerals.

Geological environment

## Genesis Goryainovite forms as a result of metasomatic processes within ultramafic alkaline complexes. At its type locality (Kovdor massif), it is associated with calcitic carbonatites that cut foidolite rocks (ijolites). ## Mineral associations This mineral coexists with minerals such as apatite (often as inclusions within it), calcite, dolomite, forsterite, magnetite, as well as rarer minerals like rimkorolgite and kamiokite. ## Localities The only confirmed locality for goryainovite worldwide is its type locality – the phlogopite and vermiculite quarry in the Kovdor massif on the Kola Peninsula, Murmansk Oblast, Russia.

Rarity

Extremely rare

For collectors

## Quality criteria As a microscopic mineral, goryainovite is not acquired for aesthetic purposes. Its collector's value is purely scientific and systematic. For collectors specializing in rare minerals or minerals from specific localities (so-called "micromounts"), the most valuable specimen will be one with the largest, well-documented analytical concentration of this mineral, originating from the type locality.

Care and storage

## Cleaning Due to the small size of the grains and their occurrence as inclusions, mechanical cleaning is usually neither possible nor necessary. If the specimen requires it, compressed air can be used to remove dust. ## What to avoid Avoid contact with strong acids, which can react with phosphates. Due to its hardness (5 on the Mohs scale), it is susceptible to scratching by harder minerals, such as quartz. ## Storage Specimens containing goryainovite should be stored under stable conditions, away from chemicals and dust. It is best to keep them in closed display boxes to protect them from mechanical damage and contamination.

Sources

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