Ruizite
Ruizite is a sorosilicate mineral with formula Ca2Mn2Si4O114·2H2O. 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 is translucent and orange to red-brown in color with an apricot yellow streak. The mineral occurs as euhedral prisms up to or as radial clusters of acicular 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.
Crystal structure and chemistry
Ruizite crystallizes in the monoclinic crystal system and twinning is common along the miller index| plane between exactly two crystals. Ruizite's formula was originally identified as CaMn22·2H2O in 1977. In 1984, Frank C. Hawthorne revised the formula to Ca2Mn2Si4O114·2H2O. Ruizite's structure consists of edge-sharing Mnφ6 octahedra, connected at corners into sheets and together into a lattice by clusters of Si4O112.Nitric acid, hydrochloric acid, and potassium hydroxide have little effect on ruizite at low temperatures but readily dissolve the mineral at elevated temperatures.