Rhodonite

Class: Silicates
Group: Rhodonite

Varieties | Names:

In manganese-bearing deposits formed by hydrothermal, contact and regional metamorphic, and sedimentary processes (Anthony et al., 2001—2005).

Orlets — specimen 0741, photo © NMNHS

Original description: ‘Rhodonit’ [Germar, E. F., 1819. Ueber die kohlenstoff- und kieselsauren Manganerze des Unterharzes — Journal für Chemie und Physik 26: 113 view in ‘Library’] Jasche, C. F., 1817. Das Rothmanganerz in der Gegend von Elbingerode am Harz — Kleine Mineralogische Schriften 1: 1—9 [view in ‘Library’].

Type locality: Kaiser Franz mine (König Wilhelm mine), Schävenholz, Elbingerode, Harz, Saxony-Anhalt, Germany.

Type material: unknown.

Etymology: from the Greek ρόδον for ‘rose’, referring to its colour.

Distribution: Australia: New South Wales; Brazil: Minas Gerais; Russia: Ural, Sverdlovskaya Oblast; USA (Anthony et al., 2001—2005).

Chemistry

CaMn3Mn(Si5O15)

Essential elements: oxygen (O), silicon (Si), manganese (Mn).

Crystal data

Crystallography: triclinic — pinacoidal. Crystal habit: crystals rough, typically tabular. Twinning: lamellar, with {010} as composition plane (Anthony et al., 2001—2005).

Physical properties

Cleavage: perfect on {110} and {110}, good on {001} (Anthony et al., 2001—2005). Fracture: conchoidal to uneven (Anthony et al., 2001—2005). Tenacity: no data. Hardness: 5.5—6.5 (Anthony et al., 2001—2005). Density: 3.57—3.76 g/cm3 (Anthony et al., 2001—2005). Luminescence: none.

Optical properties

Colour: rose-pink to brownish red, grey, or yellow; in thin section, colourless to faint pink (Anthony et al., 2001—2005). Diaphaneity: transparent to translucent (Anthony et al., 2001—2005). Lustre: vitreous (Anthony et al., 2001—2005). Refractive index: 1.711—1.748 — anisotropic [biaxial (+)] (Anthony et al., 2001—2005). Birefringence: 0.013. Dispersion: no data. Pleochroism: weak; X = yellowish red; Y = pinkish red; Z = pale yellowish red (Anthony et al., 2001—2005).

Material from ‘Repository’

1 specimen: 0741 — 2.55 ct, Russia, Ural Federal District, Sverdlovsk Oblast, Sysertsky District, Middle Urals, Malosedel’nikovskoe deposit, 56.646111°N 60.740278°E.

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