Junitoite is a mineral with formula CaZn₂Si₂O₇·H₂O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1976. The mineral is named for mineral chemist

Jun Ito Jun or JUN may refer to: People and anthroponymy * Lee Jun-young, South Korean singer and actor with the stage name Jun, member of South Korean boy band U-KISS * Wen Junhui, Chinese singer and actor with the stage name Jun, member of South Korean ...

(1926–1978).

Description and occurrence

Junitoite is transparent to translucent and is colorless, milk-white, or colored due to alteration. Crystals grow up to and have high quality faces. Junitoite occurs in fractures through pods of

sphalerite Sphalerite is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in Sedimentary exhalative deposits, sedimentary exhalative, Carbonate-hoste ...

. It formed by

retrograde metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of c ...

and oxidation of tactite, also resulting in kinoite. The mineral is known from New Jersey and the type locality in Arizona. Junitoite occurs in association with

apophyllite The name apophyllite refers to a specific group of phyllosilicates, a class of minerals. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup that compris ...

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 ...

, kinoite,

smectite A smectite (; ; ) is a mineral mixture of various swelling sheet silicates (phyllosilicates), which have a three-layer 2:1 (TOT) structure and belong to the clay minerals. Smectites mainly consist of montmorillonite, but can often contain secon ...

, and xonotlite.

Crystal structure

In 1968, Jun Ito published the results of synthesis of various lead calcium zinc silicates. The formula of one phase, designated ''X₃'', was identified as probably CaZnSi₂O₆·H₂O. When he described junitoite, Sidney Williams identified the mineral's formula as CaZn₂Si₂O₇·H₂O, based on communications with Ito. The mineral's

crystal structure In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat ...

was first determined in 1985 and refined in 2012. The mineral crystallizes in the

orthorhombic crystal system In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with ...

. The structure is formed by chains of corner-sharing ZnO₄ tetrahedra linked together by Si₂O₇ tetrahedral pairs. Calcium ions occupy vacancies and coordinate to five oxygen atoms and one water molecule.

History

The first known specimen of junitoite was collected from the Christmas mine at Christmas, Arizona, and entered the collection of Joe Ana Ruiz. Geologist Robert A. Jenkins noticed the mineral in kinoite specimens, submitting Ruiz's sample to Sidney A. Williams for study. Further samples came from the collections of Ruiz and Raymond Diaz. Williams identified the specimens as a new mineral and described it in the journal ''American Mineralogist'' in 1976. He named it ''junitoite'' in honor of Jun Ito, the mineral chemist who noted the compound of which the mineral is composed. 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. ...

approved the mineral as IMA 1975-042. The type material is housed in the

University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a Public university, public Land-grant university, land-grant research university in Tucson, Arizona, United States. Founded in 1885 by the 13th Arizona Territorial Legislature, it ...

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

, the

National Museum of Natural History The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...

, the

University of Paris The University of Paris (), known Metonymy, metonymically as the Sorbonne (), was the leading university in Paris, France, from 1150 to 1970, except for 1793–1806 during the French Revolution. Emerging around 1150 as a corporation associated wit ...

, the National School of Mines, and

The Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more ...

References

;Bibliography * * *

External links

{{commons category, Junitoite
Images of junitoite
from mindat.org Calcium minerals Zinc minerals Hydrates Sorosilicates Orthorhombic minerals Minerals in space group 40 Minerals described in 1976