Neighborite is a mineral composed of a double fluoride salt of sodium and magnesium. It was initially recognized as pink and brown masses of round grains in the

Green River Formation The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River (Colorado River), Green River in Colorado, Wyoming, and Utah. The sedimen ...

South of

Ouray, Utah Ouray is an unincorporated village of the Uintah and Ouray Indian Reservation, located in west‑central Uintah County, Utah, United States. Description The community is located primarily on the north bank of the confluence of the Duchesne ...

. Originally found in dark dolomitic oil shales, neighborite typically forms as subrounded or octahedral crystals. Neighborite received its name from Frank Neighbor, a geologist for the Sun Oil Co. based in Salt Lake City, Utah. Due to Mr. Neighbor's work in discovering neighborite, along with other newly discovered minerals to the Green River Formation, the mineral was named after him. Neighborite is in the family of

perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure as , known as the perovskite (stru ...

crystal structure minerals, possessing a general formula of ABX₃.

Occurrence

Neighborite is found in association with minerals such as burbankite,

nahcolite Nahcolite is a soft, colourless or white carbonate mineral with the composition of sodium bicarbonate ( Na H C O3) also called thermokalite. It crystallizes in the monoclinic system. Nahcolite was first described in 1928 for an occurrence in a ...

wurtzite Wurtzite is a zinc and iron sulfide mineral with the chemical formula , a less frequently encountered Polymorphism (materials science), structural polymorph form of sphalerite. The iron content is variable up to eight percent.Palache, Charles, H ...

barytocalcite Barytocalcite is an anhydrous barium calcium carbonate mineral with the chemical formula Ba Ca( C O3)2. It is trimorphous with alstonite and paralstonite, that is to say the three minerals have the same formula but different structures. Baryte ...

, garrelsite,

pyrite The mineral pyrite ( ), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

, and

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 ...

. The mineral most commonly occurs on top of dark colored dolomitic oil shales. The resulting grains are subrounded in shape. Some neighborite crystals form as inclusions in barytocalcite. Octahedral crystals of neighborite exist in nature, but is generally uncommon relative to the subangular crystals. Neighborite is a rare mineral, only being found in select localities around the world. Regions where neighborite is currently found include select wells in or near Ouray, Utah;

Montreal, Quebec Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...

;

Oslo, Norway Oslo ( or ; ) is the Capital city, capital and List of towns and cities in Norway, most populous city of Norway. It constitutes both a Counties of Norway, county and a Municipalities of Norway, municipality. The municipality of Oslo had a populat ...

;

Murmansk Oblast, Russia Murmansk Oblast is a federal subject (an oblast) of Russia, located in the northwestern part of the country, with a total land area of . Its only internal border is the Republic of Karelia to the south, and it is bordered internationally by Fin ...

; Arusha, Tanzania.

Physical properties

Neighborite is a colorless or pink to brown colored mineral exhibiting a vitreous luster. It exhibits a hardness of 4.5 on the Mohs hardness scale. It does not portray any specific cleavage planes, but instead exhibits an uneven fracture. Neighborite is insoluble in distilled water, but dissolves at a quicker rate with increased acidic conditions.

Optical properties

Neighborite is an anisotropic mineral, meaning it has more than one refractive index. However, the

birefringence Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefrin ...

of the mineral is rather low, at 0.003. The measured refractive indexes are 1.364±0.002. The octahedral crystals of neighborite occasionally exhibit twinning. cubic faces also exist as truncations.

Chemical properties

Neighborite belongs to the perovskite family of minerals. These minerals have a general formula of ABX₃. The structure consists of B atoms in an octahedron, with A and X atoms forming the cubic and octahedral cells of the structure, respectively. Perovskites are most notably used as

solar cells A solar cell, also known as a photovoltaic cell (PV cell), is an electronic device that converts the energy of light directly into electricity by means of the photovoltaic effect.

, achieving a general efficiency of around 25%.

Chemical composition

X-ray crystallography

Neighborite is an orthorhombic mineral, containing the space group ''Pcmn''. The unit cell dimensions are a=5.363 Å, b=7.676 Å, c=5.503 Å, α=90.00°, β=90.00°, γ=90.00°. The dimensions of neighborite are extremely similar to those of a basic perovskite structure. It is therefore considered part of the perovskite supergroup of minerals. As higher temperatures are achieved, the three axes lengths of neighborite get closer together. At 900°C, the axes lengths are equal, giving neighborite a cubic cell. However, this cubic structure cannot be

quenched In materials science, quenching is the rapid cooling of a workpiece in water, gas, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such a ...

, and can only exist at the high temperature range.

References

{{Authority control Fluorine minerals Orthorhombic minerals Minerals in space group 47