Ruizite is a

sorosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually con ...

mineral with formula Ca₂Mn₂Si₄O₁₁(OH)₄·2H₂O. 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 1977. The mineral is named for discoverer Joe Ana Ruiz.

Description and occurrence

Ruizite is translucent and orange to red-brown in color with an apricot yellow streak. The mineral occurs as

euhedral Euhedral crystals (also known as idiomorphic or automorphic crystals) are those that are well-formed, with sharp, easily recognised faces. The opposite is anhedral (also known as ''xenomorphic'' or ''allotriomorphic''): a rock with an anhedral ...

prisms up to or as radial clusters of acicular (needle-like) crystals. Ruizite is common at the Christmas mine. The mineral is known from Arizona, Pennsylvania, and

Northern Cape Province The Northern Cape is the largest and most sparsely populated province of South Africa. It was created in 1994 when the Cape Province was split up. Its capital is Kimberley, South Africa, Kimberley. It includes the Kalahari Gemsbok National Park, ...

, South Africa. Ruizite 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 ...

bornite Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5 Fe S4 that crystallizes in the orthorhombic system (pseudo-cubic). Appearance Bornite has a brown to copper-red color on fresh surfaces that tarnishes to v ...

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 ...

, chalcopyrite, datolite, diopside, grossular,

inesite Inesite is a hydrous calcium manganese silicate mineral. Its chemical formula is Ca2Mn7Si10O28(OH)2•5(H2O). Inesite is an inosilicate with a triclinic crystal system. It has a Mohs hardness of 5.5 to 6, and a specific gravity of 3.0. Its name ...

, junitoite,

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

, orientite, pectolite,

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

, smectite,

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 ...

, vesuvianite, and wollastonite. Ruizite is found in veinlets or fracture surfaces of limestone metamorphosed into a calc-silicate assemblage. The mineral 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 chem ...

during cooling of a calc–silicate skarn assemblage in an oxidizing environment.

Crystal structure and chemistry

Ruizite crystallizes in the

monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic sy ...

and twinning is common along the plane between exactly two crystals. Ruizite's formula was originally identified as CaMn(SiO₃)₂(OH)₂·2H₂O in 1977. In 1984, Frank C. Hawthorne revised the formula to Ca₂Mn₂Si₄O₁₁(OH)₄·2H₂O. Ruizite's structure consists of edge-sharing Mnφ₆ octahedra, connected at corners into sheets and together into a lattice by clusters of Si₄O₁₁(OH)₂.

Nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

, and

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...

have little effect on ruizite at low temperatures but readily dissolve the mineral at elevated temperatures.

History

During the investigation of junitoite at the Christmas mine in

, Joe Ana Ruiz and Robert Jenkins discovered an unknown brown mineral. Mine geologist Dave Cook located better specimens, and it was determined to be a new mineral species. The mineral was named ''ruizite'' in honor of Joe Ruiz as discoverer. Ruizite's properties were analyzed using a sample provided by Joseph Urban, and it was described in the journal ''Mineralogical Magazine'' in December 1977. 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 1977-077.

Type specimens In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes t ...

are housed in the

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

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

, the

National Museum of Natural History The National Museum of Natural History 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. In 2021, with 7 ...

, and The Natural History Museum.

References

;Bibliography * *

External links

{{Manganese minerals Monoclinic minerals Minerals in space group 14 Calcium minerals Manganese(III) minerals Sorosilicates Hydrates

Description and occurrence

Crystal structure and chemistry

History

See also

References

Further reading

External links