Roweite

roweite

olshanskiite

shimazakiite

uralborite

Images

Formula: Ca2Mn2+2B4O7(OH)6
Tetraborate, manganese-bearing mineral, forms a series with fedorovskite
Crystal system: Orthorhombic
Luminescence: Not fluorescent
Specific gravity: 2.935 measured, 2.939 calculated, 2.92 calculated for the empirical formula for roweite from the Fuka mine
Hardness: 4½ to 5
Colour: Light brown; colourless in transmitted light
Solubility: Perfectly soluble in dilute hydrochloric acid
Environments

Sedimentary environments
Metamorphic environments

Localities

At the Shijiangshan mine, Hexigten Banner, Chifeng City, Inner Mongolia, China, aggregates of between laminar and tabular roweite crystals of great size and quality have been found. They are on matrix with small andradite crystals with a light creamy colour, and partially coated by groups of white olshanskyite crystals (Mindat photo).
Roweite from the Shijiangshan Mine - Image

At the Fuka mine, Fuka, Bitchū, Takahashi City, Okayama Prefecture, Japan, roweite was discovered as aggregates of several fine crystals in a borate mineral assemblage block. The block mainly consists of shimazakiite in crystalline limestone close to gehlenitespurrite skarns. These skarns were formed as pyrometasomatic products of limestone. Several roweites occur as an aggregate of radial column crystals and a granular crystal from 0.1 to 0.8 mm across in an uralborite crystal, which is one of the minerals in the block consisting of uralborite and frolovite without shimazakiite in the crystalline limestone. Roweite seems to replace uralborite. The other associated minerals are bultfonteinite, calcite and fluorite.
Roweite is reddish brown or dark brown with a vitreous lustre in hand specimens. In thin section, the mineral is pale yellowish brown to dark brown and transparent (Journal of Mineralogical and Petrological Sciences 110.29–34).

At the type locality, the Franklin Mine, Franklin, Sussex County, New Jersey, USA, roweite was found in a narrow veinlet in very close association, and in places intergrown, with clinochrysotile, but with no associated thomsonite (as had been reported earlier, presumably erroneously). The wall-forming minerals of the roweite veinlet are franklinite, zincite and willemite; inclusions of these minerals are sparse in some roweite crystals. The most abundant included material, however, is clinochrysotile with which roweite may occur as parallel or, less commonly, as complex intergrowths. Roweite replaces anhedral masses of calcite which are in optical continuity throughout a roweite crystal and which show effects of solution. Much of the roweite, however, is essentially free from inclusions of any kind (AM 59.66-70).
Roweite from the Franklin Mine - Image

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