Ruizite

Ruizite
Clusters of ruizite on calcite from South Africa
General
Category	Sorosilicate
Formula (repeating unit)	Ca2Mn2Si4O11(OH)4·2H2O
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

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.

Ruizite is translucent and orange to red-brown in color with an apricot yellow streak. The mineral occurs as euhedral prisms up to 1 mm (0.039 in) 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, South Africa. Ruizite occurs in association with apophyllite, bornite, calcite, chalcopyrite, datolite, diopside, grossular, inesite, junitoite, kinoite, orientite, pectolite, quartz, smectite, sphalerite, 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 during cooling of a calc–silicate skarn assemblage in an oxidizing environment.