Baratovite is a very rare

cyclosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, the crystalline forms of silica (silicon dio ...

mineral named after Rauf Baratovich Baratov from Tajikistan. It was discovered in 1974 at Dara-Pioz glacier, Tajikistan, and was approved by the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. ...

only a year later in 1975. The glacier gives home to 133 valid species, and is the type locality of 33 minerals, one of which is baratovite.

Properties

It's a titanium rich variant of aleksandrovite. Although it is considered to be rich in titanium, and the fact it is the fluor-dominant analog of katayamalite, some mineralogist consider baratovite to be a hydroxyl-, rather than fluorine-dominant. In this case, it would make katayamalite the same species, as baratovite is

isostructural Isostructural chemical compounds have similar chemical structures. " Isomorphous" when used in the relation to crystal structures is not synonymous: in addition to the same atomic connectivity that characterises isostructural compounds, isomorphous ...

with it. Common impurities include

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

, natrium,

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

and

niobium Niobium is a chemical element; it has chemical symbol, symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and Ductility, ductile transition metal. Pure niobium has a Mohs scale of mineral hardness, Mohs h ...

. Baratovite was originally described to have a 3 - 3.5 hardness on the Mohs scale, which was later corrected to 5 - 6. It has a perfect cleavage in two directions crossing basal plane, in , and the luster of the mineral is pearly on the cleavages. It consists mainly of oxygen (40.88%), silicon (23.92%) and calcium (19.91%), but also contains titanium (5.10%), zirconium (3.24%), potassium (2.78%), fluorine (2.70%) and lithium (1.48%). It has a barely detectable, 39.51 radioactivity, measured in

Gamma Ray American Petroleum Institute Units Gamma (; uppercase , lowercase ; ) is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter normally repr ...

. The concentration per GRapi units in percentage is 2.53. It is the end member of the series. The mineral also shows

fluorescent Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...

properties. Inspected under short wavelength

ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

, it has a blueish white fluorescence. The mineral is similar to

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula KAl2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage y ...

, but can be distinguished by its fluorescence. Baratovite can either be colorless, white, or have pinkish tints. It forms platy deposits up to 5 cms that are

nacre Nacre ( , ), also known as mother-of-pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer. It is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is ...

-white, and it grows in patchy granular aggregates. The mineral is monoclinic, probably pseudo-hexagonal, which is shown by the single crystal X-ray study. When inspected under a microscope, it can be clearly seen that the mineral is perfectly homogeneous. The mineral has an extremely low

anisotropy Anisotropy () is the structural property of non-uniformity in different directions, as opposed to isotropy. An anisotropic object or pattern has properties that differ according to direction of measurement. For example, many materials exhibit ve ...

Occurrences

It's a type locality of Dara-Pioz glacier, Tajikistan, but it also occurs at the Iwagi islet, Japan. It occurs as an accessory mineral. It occurs in the form of veinlets in quartzes, albites and aegirines, and in albitites in syenites. Minerals associated with baratovite vary between localities. The associated minerals of baratovite specimens found in Dara-i-Pioz massif, Tajikistan are:

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

albite Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a tectosilicat ...

ekanite Ekanite is an uncommon silicate mineral with chemical formula or . It is a member of the steacyite group. It is among the few gemstones that are naturally radioactive. Most ekanite is mined in Sri Lanka, although deposits also occur in Russia and ...

titanite Titanite, or sphene (), is a calcium titanium nesosilicate mineral, Ca Ti Si O5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals including cerium and yttrium; calcium may be partly rep ...

aegirine Aegirine is a member of the clinopyroxene group of inosilicate minerals. It is the sodium endmember of the aegirine– augite series. It has the chemical formula NaFeSi2O6, in which the iron is present as the ion Fe3+. In the aegirine–augite se ...

and miserite. Associated minerals of biotite from Iwagi islet, Japan are:

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of th ...

pectolite Pectolite is a white to gray mineral, Na Ca2 Si3 O8(O H), a sodium calcium hydroxide inosilicate. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a spec ...

, sugilite,

allanite Allanite (also called orthite) is a sorosilicate group of minerals within the broader epidote group that contain a significant amount of rare-earth elements. The mineral occurs mainly in metamorphosed clay-rich sediments and felsic igneous rocks. ...

, titanite, aegirine and albite.

References

{{Reflist Cyclosilicates Monoclinic minerals