freeform step-cut pyroxmangite - Brazil
freeform step-cut pyroxmangite - Brazil

Pyroxmangite Value, Price, and Jewelry Information


Pyroxmangite grains are rare, seldom clean enough to facet, and difficult to cut. However, when cut, they are extremely beautiful and rich in color.

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Pyroxmangite grains are rare, seldom clean enough to facet, and difficult to cut. However, when cut, they are extremely beautiful and rich in color.

freeform step-cut pyroxmangite - Brazil
Medium-dark red, freeform step-cut pyroxmangite, 0.72-ct, 7.9 x 4.1 mm, Minas Gerais, Brazil. © The Gem Trader. Used with permission.
faceted pyroxmangite - Japan
Pyroxmangite: Japan (0.55). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Comments

Although pyroxmangites can show stunning transparent red colors, from reddish brown to purplish pink, these rare gems have perfect cleavage in two directions. This makes them difficult for faceters to cut and means they have great susceptibility to fracture from blows, thus, you'll rarely see them used as jewelry stones.

Pyroxmangite forms a series with pyroxferroite. In pyroxferroites, the iron (Fe) content exceeds the manganese (Mn) content. (The pyroxmangite type material from South Carolina later proved to be pyroxferroite).

Pyroxmangites are also polymorphous with the popular gem material known as rhodonite, sharing the same chemical structure. Sometimes, they occur together.

pyroxmangite, rhodonite, and todorokite - Catalonia
Pyroxmangite and rhodonite (pale pink) with todorokite (black), Serrana mine, Priorat (Catalonia). Photo by Darth vader 92. Licensed under CC By-SA 4.0.

Identifying Characteristics

Even professional gem labs may have difficulty distinguishing pyroxmangites from rhodonites. Although rhodonites may have slightly lower refractive index (RI), birefringence, and specific gravity (SG) values, these properties as well as their colors, pleochroism, optic character, and hardness may largely overlap. Sometimes, a powder X-ray diffraction (XRD) analysis may be needed.

Synthetics

Scientists have synthesized pyroxmangite to study its polymorphism with rhodonite. However, there is no known jewelry use for this synthetic material.

Enhancements

None known.

massive pyroxmangite slab - Colorado
Polished slab of massive pyroxmangite, 10.2 x 6.1 x 0.6 cm, Sunnyside Mine (American Tunnel; Mogul Mine; Washington Mine; Belle Creole; Gold Prince; Brenneman Mine; Sunnyside Mine Group), Howardsville, Silverton District, San Juan Co., Colorado. © Rob Lavinsky, www.iRocks.com. Used with permission.

Sources

Honshu, Japan and Brazil have produced gemmy material. Other notable sources include the following:

  • United States: Kern County, California; Colorado; Boise, Idaho (pale pink material).
  • Australia: Broken Hill, New South Wales (in fine crystals and grains, with rhodonite).
  • Finland (brown); Peru; Spain; Sweden (red-brown); Scotland, United Kingdom.

Stone Sizes

Any faceted pyroxmangites are always small, since the material is extremely scarce and available only as small transparent grains, but faceters can cut large cabochons from cleavages and massive materials. Collectors should expect to see stones up to about 2 carats.

Care

Due to their cleavage, don't clean pyroxmangites with mechanical systems such as ultrasonic or steam. Clean these gems only with a warm damp cloth, mild detergent, and soft brush. For more care recommendations, consult our gemstone jewelry cleaning guide.

pyroxmangite crystals - Japan
Cherry-red pyroxmangites in matrix, 6 mm crystals, Taguchi mine, Shidara, Kita-Shidara-gun, Aichi Prefecture, Chubu Region, Honshu Island, Japan. © Rob Lavinsky, www.iRocks.com. Used with permission.

Joel E. Arem, Ph.D., FGA

Dr. Joel E. Arem has more than 60 years of experience in the world of gems and minerals. After obtaining his Ph.D. in Mineralogy from Harvard University, he has published numerous books that are still among the most widely used references and guidebooks on crystals, gems and minerals in the world.

Co-founder and President of numerous organizations, Dr. Arem has enjoyed a lifelong career in mineralogy and gemology. He has been a Smithsonian scientist and Curator, a consultant to many well-known companies and institutions, and a prolific author and speaker. Although his main activities have been as a gem cutter and dealer, his focus has always been education. joelarem.com


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