Nioboholtite is an extremely rare mineral with the formula (Nb_0.6[]_0.4)Al₆BSi₃O₁₈. It is the

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 ...

-rich member of the dumortierite supergroup, and the

analogue of holtite of the holtite group. It is one of three quite recently found minerals of this group, the other two being

titanoholtite Titanoholtite is an extremely rare mineral with the formula (Ti0.75[]0.25)Al6BSi3O18. It is titanium-rich member of dumortierite supergroup, and titanium-analogue of holtite of the holtite group. It is one of three quite recently found minerals of ...

and szklaryite, all coming from the Szklary village near

Ząbkowice Śląskie Ząbkowice Śląskie ( ; ) is a town in Lower Silesian Voivodeship, in south-western Poland. It is the seat of Ząbkowice Śląskie County and of a local municipality called Gmina Ząbkowice Śląskie. The town lies approximately south of the ...

in Poland. They occur in a unique

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic c ...

. Nioboholtite and

schiavinatoite Schiavinatoite is a very rare borate mineral, and the niobium endmember of a solid solution formed with béhierite.Demartin, F., Diella, V., Gramaccioli, C.M., and Pezzotta, F., 2001. Schiavinatoite, , the Nb analogue of behierite. European Journ ...

are both minerals with essential

and

boron Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three ...

Association

Nioboholtite is mainly associated with holtite and a number of other minerals (see szklaryite).

Notes on chemistry

Main impurities in nioboholtite are

antimony Antimony is a chemical element; it has chemical symbol, symbol Sb () and atomic number 51. A lustrous grey metal or metalloid, it is found in nature mainly as the sulfide mineral stibnite (). Antimony compounds have been known since ancient t ...

and

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

, with trace or minor

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

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 ...

tantalum Tantalum is a chemical element; it has Symbol (chemistry), symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. Tantalum is a very hard, ductility, ductile, lustre (mineralogy), lustrous, blue-gray transition ...

titanium Titanium is a chemical element; it has symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

and

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

groups.

References

Silicate minerals Niobium minerals Aluminium minerals Borate minerals Orthorhombic minerals Minerals in space group 62 Borosilicates {{silicate-mineral-stub