Tokyoite is a rare

barium Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. Th ...

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

vanadate In chemistry, a vanadate is an anionic coordination complex of vanadium. Often vanadate refers to oxoanions of vanadium, most of which exist in its highest oxidation state of +5. The complexes and are referred to as hexacyanovanadate(III) and no ...

mineral with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

: Ba₂(Mn³⁺,Fe³⁺)OH(VO₄)₂. It is the manganese analogue of the iron rich gamagarite and the barium analogue of the lead vanadate, brackebuschite. It occurs in low-grade

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

sedimentary manganese

ore deposit Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

s associated with

hyalophane Hyalophane or jaloallofane is a crystalline mineral, part of the feldspar group of tectosilicates. It is considered a barium-rich potassium feldspar. Its chemical formula is , and it has a hardness of 6 to . The name ''hyalophane'' comes from the ...

braunite Braunite is a silicate mineral containing both di- and tri- valent manganese with the chemical formula: Mn2+Mn3+6 SiO4 Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium. Braunite forms grey/black tetragon ...

and tamaite. It was first reported for an occurrence in the Shiromaru Mine, Okutama, Tama district,

Tokyo Prefecture Tokyo, officially the Tokyo Metropolis, is the capital and most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is one of the most populous urban areas in the world. The Greater Tokyo Area, which ...

Kantō region The is a geography, geographical region of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures of Japan, prefectures: Chiba Prefecture, Chiba, Gunma Prefe ...

Honshu Island , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

and approved by the

IMA IMA or Ima may refer to: Education * Indian Military Academy, Dehradun * Instituto Miguel Ángel, a school in Mexico City Galleries and museums * Indianapolis Museum of Art, Indiana, US * Institut du Monde Arabe, Paris, France * Islamic Mus ...

in 2003. It has been found in two mines in

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

and one in

, for which it was named.

References

Vanadate minerals Monoclinic minerals Minerals described in 2003 {{oxide-mineral-stub