Millerite Value, Price, and Jewelry Information

Does Millerite Make a Good Jewelry Stone?

Although massive millerite occurs abundantly at certain locations, it generates little interest from jewelry enthusiasts. Its very low hardness (3 to 3.5) and perfect cleavage in two directions make it unsuitable for wear. Thus, as gem material for cabochons and even decorative objects, it rarely appears on the market. You're more likely to find cut millerites in rare gem collections, if at all, than jewelry collections.

Why is Millerite Sometimes Called "Hair Pyrite"?

As sprays of very thin capillary or filiform crystals, however, millerites take on an unusual, almost organic appearance. Sometimes called "hair pyrites," these millerites indeed resemble tufts of hair growing within geodes. These millerite formations are also flexible and soft and make very interesting additions to mineral and crystal collections.

Please note that millerite and pyrite are distinct mineral species. In the nickname "hair pyrite," pyrite refers to millerite's metallic luster and color.

How to Identify Millerite

Millerites show very weak pleochroism when viewed normally in air. However, in oil, they display more strongly. They show pale yellow-brown color on the ordinary ray and bright yellow color on the extraordinary ray.

Millerite leaves a greenish black streak. Keep in mind that streak testing can destroy the test sample. Conduct this examination only as a last resort for gem identification on rough, never on a finished gem.

Are There Synthetic Millerites?

Millerite serves as an important ore for the metal nickel. Thus, scientists use synthetic millerites to study the extraction of nickel from this mineral in laboratory settings. However, jewelry use of this lab-made material is unknown.

There are no known gemstone treatments for millerites.

Where is Millerite Found?

Antwerp, New York produces fine sprays of acicular crystals. The Gap Mine in Lancaster County, Pennsylvania produces acicular tufts.

Halls Gap, Kentucky and Missouri yield millerites as tufts of fibers in geodes.

Timagami, Ontario, Canada produces large cleavable masses.

Other notable sources include the following:

• United States: Illinois; Wisconsin; Iowa.
• Czech Republic; Germany; Slovakia; United Kingdom (Wales).

Stone Sizes

From massive material, gem cutters could cut cabochons or slabs of any size.

Caring for Millerites

See our gemstone jewelry cleaning guide for care recommendations.