Junitoite is a mineral with formula CaZn₂Si₂O₇·H₂O. It was discovered at the Christmas mine in

Christmas, Arizona Christmas is an uninhabited mining community in Gila County, Arizona, Gila County, Arizona, United States. The mine which led to creation of the town was Land claim#Staking a claim, staked on Christmas Day 1902, prompting the name. During the thr ...

, and described in 1976. The mineral is named for mineral chemist Jun Ito (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 (sometimes spelled sphaelerite) 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, sedimen ...

. It formed by retrograde metamorphism and oxidation of tactite, also resulting in kinoite. The mineral is known from New Jersey and the

type locality Type locality may refer to: * Type locality (biology) * Type locality (geology) See also * Local (disambiguation) * Locality (disambiguation) {{disambiguation ...

in Arizona. Junitoite occurs in association with apophyllite,

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 Kinoite ( or
at Mindat.org ) is a light blue copper silicate mineral. It is somewhat scarce. It has a monoclinic crystal system, ...

, smectite, 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 was first determined in 1985 and refined in 2012. The mineral crystallizes in the orthorhombic crystal system. 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

, and entered the collection of Joe Ana Ruiz. Geologist Robert A. Jenkins noticed the mineral in

kinoite Kinoite ( or
at Mindat.org ) is a light blue copper silicate mineral. It is somewhat scarce. It has a monoclinic crystal system, ...

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. Th ...

approved the mineral as IMA 1975-042. The type material is housed in the University of Arizona, Harvard University, the National Museum of Natural History, the University of Paris, the National School of Mines, and The Natural History Museum.

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