Ruizite

Ruizite
Clusters of ruizite on calcite from South Africa
General
Category	Sorosilicate
Formula (repeating unit)	Ca2Mn2Si4O11(OH)4·2H2O[1]
IMA symbol	Rz[2]
Strunz classification	9.BJ.35
Dana classification	57.2.2.1
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	P21/c
Unit cell	a = 11.95 Å, b = 6.17 Å c = 9.03 Å, β = 91.37°; Z = 4
Identification
Color	Orange, red-brown
Twinning	Common on {100}
Mohs scale hardness	5
Streak	Apricot
Diaphaneity	Translucent
Optical properties	Biaxial (-)
Refractive index	nα = 1.663 nβ = 1.715 nγ = 1.734
Birefringence	δ = 0.071
2V angle	60°
References	[3]

Ruizite is a sorosilicate mineral with formula Ca₂Mn₂Si₄O₁₁(OH)₄·2H₂O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1977. The mineral is named for discoverer Joe Ana Ruiz.

Description and occurrence[]

Ruizite from Arizona

Ruizite is translucent and orange to red-brown in color with an apricot yellow streak.^[3] The mineral occurs as euhedral prisms up to 1 mm (0.039 in) or as radial clusters of acicular (needle-like) crystals.^[1]

Ruizite is common at the Christmas mine.^[4] The mineral is known from Arizona, Pennsylvania, and Northern Cape Province, South Africa.^[3] Ruizite occurs in association with apophyllite, bornite, calcite, chalcopyrite, datolite, diopside, grossular, inesite, junitoite, kinoite, , pectolite, quartz, smectite, sphalerite, vesuvianite, and wollastonite.^[1] Ruizite is found in veinlets or fracture surfaces of limestone metamorphosed into a calc-silicate assemblage. The mineral formed by retrograde metamorphism during cooling of a calc–silicate skarn assemblage in an oxidizing environment.^[1][4]

Crystal structure and chemistry[]

Ruizite crystallizes in the monoclinic crystal system and twinning is common along the {100} plane between exactly two crystals.^[1] Ruizite's formula was originally identified as CaMn(SiO₃)₂(OH)₂·2H₂O in 1977.^[4] In 1984, Frank C. Hawthorne revised the formula to Ca₂Mn₂Si₄O₁₁(OH)₄·2H₂O.^[5] 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.^[6]

Nitric acid, hydrochloric acid, and potassium hydroxide have little effect on ruizite at low temperatures but readily dissolve the mineral at elevated temperatures.^[7]

History[]

During the investigation of junitoite at the Christmas mine in Christmas, Arizona, 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.^[8] The International Mineralogical Association approved the mineral as IMA 1977-077.^[9] Type specimens are housed in the University of Arizona, Harvard University, the National Museum of Natural History, and The Natural History Museum.^[1]

See also[]

• Carlosruizite

References[]

Bibliography

• Hawthorne, F. C. (1984). "The crystal structure of ruizite, a sorosilicate with an [Si₄Ø₁₃] cluster". Tschermaks mineralogische und petrographische Mitteilungen. 33 (2): 135–146. Bibcode:1984TMPM...33..135H. doi:10.1007/BF01083069.
• Williams, Sidney A.; Duggan, M. (December 1977). "Ruizite, A New Silicate Mineral from Christmas, Arizona" (PDF). Mineralogical Magazine. 41 (320): 429–432. Bibcode:1977MinM...41..429W. doi:10.1180/minmag.1977.041.320.01.

Further reading[]

• Moore, Paul B.; Shen, Jinchuan; Araki, Takaharu (January–February 1985). "Crystal chemistry of the ²_∞[M³⁺₂φ₂(TO₄)₂]sheet: structural principles and crystal structures of ruizite, macfallite and orientite" (PDF). American Mineralogist. 70 (1–2): 171–181.

External links[]

Media related to ruizite at Wikimedia Commons