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Gem Profile- Psilomelane

by Judy Ellis
Psilomelane, also rarely called psilomelanite and black hematite, is an umbrella name for manganese oxides, which are black stones. The name was chosen in 1758 and comes from the Greek for "smooth" (psilos) and "black" (melas - like melanin gives a dark pigment).
You've likely seen this stone at Tucson or other large gem shows: psilomelane, which resembles a black, metallic slice of wood.

Gem-quality psilomelane, often called crown of silver psilomelane or silver crown psilomelane, is polished to reveal silvery "wood grain" or "tree rings" on a jet-black background. Some people even refer to it as "black malachite," though the two stones are unrelated.

The name comes from the Silver Crown Mine in Chihuahua, Mexico, which has only rarely been open in the past 100 years, closing due to World War II and multiple cave-ins.

Although there was significant mining in the 1950s and some activity in the early 2000s, psilomelane remains a rare find on the lapidary market.
Judy Ellis's Gem Profile- Psilomelane - , General Education, , Psilomelane Cabochon with pyrolusite grain
The silvery areas of psilomelane, which can appear black, silver, or blue depending on the light angle, are composed of pyrolusite, a different manganese oxide.

Pyrolusite has industrial uses, including alloy production, chlorine creation, disinfectants, removing green and brown tints from glass, and in calico printing and dyeing.

Despite its hematite-like appearance, pyrolusite is not magnetic. It can also be used in batteries, though artificial substitutes are more commonly employed.

Here is a picture of that shiny pyrolusite covering a botryoidal formation.
Judy Ellis's Gem Profile- Psilomelane - , General Education, , Pyrolusite
(Wikipedia source)

Psilomelane is softer than quartz, ranking about 5 to 6 on the Mohs scale.

It often forms grape-like, botryoidal shapes, but some unusual specimens feature black, hair-like crystals on top, which can be less than a quarter-inch tall.

Outside the Silver Crown Mine in Chihuahua, Mexico, there are few active sources of gem-grade psilomelane.

In the U.S., it has been found in Augusta County, Virginia (now abandoned), Arizona, New Mexico, Montana, and Arkansas.

Small pockets also exist in Europe, Africa, Asia, and Australia.

Some psilomelane stones contain clear areas between the "grain," sometimes with druzy. This material is chalcedony, sometimes called manganese oxide in quartz, and can produce striking cabochons.

Metaphysically, psilomelane is believed to help understand emotional patterns and empower us to re-engrave those grooves for personal growth.
Resources & Recommended Reading

Pyrolusite on Wikipedia
Psilomelane on MinDat
Psilomelane on Wikipedia
Cryptomelane on Wikipedia

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