Gem Profile July 22: Rhodochrosite

Daily Wire Jewelry Making Tip for
July 22, 2011

Rhodochrosite

Rhodochrosite Facts

Rhodochrosite (Greek "rhodo" for rose and "khros" for color), whose compound name is manganese carbonate, is found in ore veins and extremely large manganese deposits. It has a grainy texture, somewhat like brown sugar, and ranges in color from a dark rose color to light pink, gray, or brown. This variation in color, which many wire artists find intriguing, is due to the varying amounts of trace compounds in the rhodochrosite. These include iron, calcium, magnesium, zinc, and cobalt. Its luster ranges from a glass-like appearance to a somewhat pearly veneer. Rhodochrosite is an excellent addition to a jewelry collection because it is so visually stimulating, although it is quite soft, so handle it carefully. Its brilliant red color and iridescence stand out when wrapped or set in a white metal, such as sterling or Argentium®, or with white gemstones or clear Swarovski® crystals.

Rhodochrosite and Similar Stones

Rhodochrosite is a 3.5 to a 4 on Mohs scale, which makes it ideal for filing and reshaping, and has a specific gravity of 3.4 to 3.6. Because pure specimens of rhodochrosite that have that spectacular rose color are very rare, impure specimens with a lighter hue of pink are commonly used and are often confused with rhodonite. The stones are very similar because rhodonite and rhodochrosite are both manganese minerals, but rhodonite much more stable compound. One way to tell these gemstones apart is by their hardness: rhodonite is a 5.5 to a 6.5 on the Mohs scale, so it is much harder than rhodochrosite. Also, Rhodonite is an opaque "gem-rock", deep pink in color, pretty consistent in color, that usually has black manganese inclusions, either in streaks or specks.

Rhodonite rarely, if ever, has any white unless it is a specimen where rhodonite crystals have formed in quartz, which is a great shelf piece, but contains many internal fractures that will most often splinter and crumble if the piece is cut on a saw. Most of the rhodochrosite on the market today has white or cream banding (the carbonate material) and resembles lace. Sometimes rhodochrosite can also have a few minuscule black, manganese inclusions, but they are not desirable to "professional" jewelry designers. As a carbonate manganese, rhodochrosite is a rather soft stone and should also be considered a "gem-rock." Rhodochrosite also has a unique cleavage; it peaks in three different directions, and there is distinct crystal twinning in most pure specimens (meaning that lines and grooves where the minerals have switched directions are quite clear). This makes the stone very hard to cut into a uniform shape, so rhodochrosite is rarely found in faceted jewelry unless cut by an experienced artisan.

Rhodochrosite History and Sources

Rhodochrosite was first discovered in the ore deposits of silver mines in Romania in 1813. Since then, it has been mined in Argentina, Japan, Peru, Russia, and South Africa. However, the most pure specimens (and the largest) of the mineral are found in the Sweet Home Mine near Alma, Colorado. Colorado named rhodochrosite its state mineral in 2002. The Denver Museum of Nature and Science now displays the world’s largest single crystal of rhodochrosite, named the "Alma King" as a tribute to the mine it came from. Before it began to be mined for collectors and jewelry-makers, rhodochrosite was often thrown away, because its chemical composition makes it extremely destructive to the blending process in the mining of silver; the presence of rhodochrosite in silver is considered to be a great impurity. Most of the good quality rhodochrosite comes from South America: Rhodochrosite was found hiding in stalactites and stalagmites of ancient caves of Argentina. Stalactites and stalagmites are large rock structures that come up from the floor and hang down from the ceiling of caves, and are made up of calcium carbonate and lime deposits. No one knew the rhodochrosite was there until one of these broke apart, revealing an amazingly red core!

Rhodochrosite in Culture

Like most gems, rhodochrosite is rich in cultural history. The Incas believed that rhodochrosite was the blood of their ancestors in solid form, so this rock is sometimes called "la Rosa Del Inca" or "the Inca Rose." The Incas wore these stones when facing enemies, believing that it would give them strength and peace of mind in times of conflict.

Because rhodochrosite is made up of manganese, it is very useful in many areas besides jewelry-making. In its base form, it can be used to supplement crops that are deficient of nutrients, can be added to ceramics to form a colorful glaze, and it is even used industrially to make concrete stains (think of those tall, rose-colored concrete walls you’ve seen surrounding residential areas). As a healing stone, it is thought to heal the heart chakra, allowing a person to become more balanced, to forgive themselves and others, to trust, and to give and receive love.

In next week’s gem profile, we’ll cover Rhodonite. Have you wire wrapped rhodonite before? Send pictures to tips@wire-sculpture.com and they could be featured!

Resources

Print Resources:

• Eyewitness Handbooks’ Rocks and Minerals by Chris Pellant, ISBN 1-56458-033-4
• Peterson Field Guide to Rocks and Minerals by Frederick H. Pough, ISBN-0-395-91096-X
• Smithsonian Rock and Gem by Ronald Louis Bonewitz, ISBN 0-7566-0962-3

Internet Resources:

• www.bernardine.com
• www.classicgems.net
• www.jegem.com
• www.wikipedia.org

Gem Profile by Wire-Sculpture Staff member Liza Roberts

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3 Comments

1. 

   Joy catinalife Adams

   July 22, 2011 at 9:07 am

   Great post, Rhodocrosite is one of my favorite stones and I have a small fortune of them. I’ve noticed over the last few years they will change color, due to exposure to air and also the content amount of manganese I believe makes this change happen. It is a very desirable stone for many, red gem grade or opaque pink, and I love to use it in my pieces.
2. 

   Robert Branson

   August 8, 2011 at 10:16 pm

   I have many pieces using this stone, and it has proved a very good seller. The extra information
   on this stone will prove very valuable, thank you.
   Robert
3. 

   Sharon Helmke

   August 26, 2011 at 10:44 am

   I am alway excited to see information of gemstones, and though I love designing necklaces, I think I am a closet rock hound. Thank you so much for the information and beautiful pictures of the stones. I help a friend sell beads at a local flea market and love to pass on tidbits about the stones people are buying, it not only helps to sell the bead but more importantly it gives the new owner a better understanding and appreciation of the stones. So again, Thanks, and keep them coming.