From Gems & Gemology: First Report of Cat’s-Eye Rhodonite

This article is published courtesy of  Gemological Institute of America‘s Gems & Gemology
Author: Brendan Laurs
Intellectual property: GIA
Photo by: Robert Weldon 

This cat’s-eye rhodonite (6.93 ct) from Brazil shows good chatoyancy. Photo by Robert Weldon.

Gems & Gemology editor Brendan Laurs prepared the following entry for the G&G Gem News International section.  

Rhodonite (MnSiO3) is an attractive pink-to-red mineral that is often sold as specimens or ornamental material, but seldom as a gemstone, since it is typically opaque and has perfect cleavage in two directions. Facetable material is very rare, and small amounts are occasionally produced from just two localities — Broken Hill, Australia, and Minas Gerais, Brazil. Some polished material has a saturated color that resembles fine spinel or rhodochrosite.

 At last month’s Gem & Jewelry Exchange show in Tucson, Luciana Barbosa (Gemological Center, Belo Horizonte, Brazil) had some attractive rhodonite cabochons showing good chatoyancy (e.g., see figure). She reported that the material was found in 2009 at Morro da Mina, near Conselheiro Lafaiete in Minas Gerais. The rhodonite is recovered as a byproduct of manganese mining, in a large open pit operated by Companhia Vale do Rio Doce. Barbosa knew of about 30 pieces of the cat’s-eye rhodonite (ranging from approximately 2 to 40 ct), and she had not seen the material previously. To her knowledge, the stones were all untreated. She indicated that the identity of the rhodonite was confirmed with X-ray diffraction analysis.
We believe this is the first report of cat’s-eye rhodonite.
For the latest gemological developments around the world, read the Gem News International section in every issue of G&G. PDF copies of the journal are available at Gems & Gemology Online. To purchase a print copy or to subscribe to G&G, visit the G&G order page or contact Circulation Coordinator Martha Rivera by calling toll-free (800) 421-7250, ext. 7142. From outside the U.S. and Canada, call (760) 603-4000, ext. 7142.

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