Rhodonite


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rhodonite

[′rōd·ən‚īt]
(mineralogy)
MnSiO3 A pink or brown mineral inosilicate crystallizing in the triclinic system and commonly found in cleavable to compact masses or in embedded grains; luster is vitreous, hardness is 5.5-6 on Mohs scale, and specific gravity is 3.4-3.7.

Rhodonite

 

a mineral of the silicate class with the chemical formula CaMn4[Si5O15]. Natural rhodonites contain 30–46 percent MnO, 4-6.5 percent CaO, and 45-48 percent SiO2, with admixtures of FeO (up to 12 percent), Zn (fowlerite), Mg, and Al. Rhodonite crystallizes in the triclinic system. The structure of the crystal lattice is represented by complex chains of two repeating diorthogroups of Si2O7 connected by SiO4 tetrahedrons, between which MnO6 and CaO6 octahedrons are distributed. Tabular and prismatic crystals are rarely found; granular and dense masses are usual. The mineral is rose-red and has a vitreous luster. It has a hardness of 5.5-6 on Mohs’ scale and a density of 3,400-3,750 kg/m3.

Rhodonite is a low-temperature mineral in hydrothermal and contact-metamorphic formations that are rich in manganese oxides and is associated with bustamite, rhodochrosite, tephroite, and manganese garnet. It is used as a face and ornamental stone. In the USSR, rhodonite deposits are found near Sverdlovsk in the Urals, where the mineral is called orlets. Other deposits are at Långban, Sweden; Conningham, Mass., USA; and Xonotla, Mexico.

References in periodicals archive ?
There were very extensive representations from the Broken Hill collections of Milton Lavers and Rod Sielecki, and I still cherish images of certain specimens of copper, rhodonite, pyromorphite,anglesite, smithsonite, cerussite ...
Large and superb crystals of translucent to gemmy, brilliant red rhodonite found in a manganese mine near Conselheiro Lafaiete, Brazil have been reaching the mineral market in recent years.
The rhodonite specimens in these cases even silenced the nay-sayers who were viewing their first museum-quality New Jersey rhodonite specimens (sharp, blocky rhodonite crystals to 15 cm on matrix!).
For exciting examples, see below under California and Venezuela gold; California ferro-axinite; Thetford Mines, Quebec andradite; Ojuela mine, Mexico mimetite and hemimorphite; Peruvian rhodonite; Madagascar liddicoatite; Kazakhstan copper; Pakistan anatase and brookite; and many more.
In February 1890 Niven received "one of the best lots of minerals from Nova Scotia I have ever seen, comprising chabazite, gmelinite, analcite, stilbite and heulandite," and also offered for sale an intriguing specimen: "the finest, largest and best rhodonite specimen that doubtless has ever been found," priced very high (for the times) at $500.
For at least 30 years, a manganese-rich skarn deposit somewhere near Conselheiro Lafaiette, Minas Gerais, has been known occasionally to produce deep pink rhodonite, very rarely in gemmy crystals (see Alvaro Lucio's 1971 note in vol.
A more satiny luster characterizes some benitoite, barite and rhodonite. The presence of lively luster rewards the viewer with visual stimulation, a quality often absent in dull-lustered crystals.
"Jewelry-industrial" and "industrial" materials range down a scale from lazurite, jadeite and nephrite at the top, through charoite, rhodonite, jasper and petrified wood, to items like "aventurine quartzite," "ophicalcite (serpentine/calcite)" and "agalmatolite (pyrophyllite/talc)," although, perhaps mercifully, the last three which merit separate chapters in the parade of chapters to follow are malachite, chalcedony and rhodonite.
Along the lower perimeter of the middle and bottom workings we have encountered a distinctly different skarn assemblage consisting of rhodonite, massive epidote, and a chocolate brown mineral in a fine-textured gray-green matrix (see under diopside).
Cerussites, fine rhodonite in galena and especially a world-class stolzite garnered the most praise.
Also in the case were specimens from the George Vaux collection including a particularly fine rhodonite from Franklin, New Jersey.