Wulfenite: Properties, Infromation, Uses

Wulfenite is a lead molybdate mineral known for its vibrant colors, ranging from orange and yellow to red and brown. It has a unique adamantine luster and forms in various crystal shapes.

Wulfenite is a rare mineral belonging to the class of minerals called molybdates and if found in large amounts it can be used for the extraction of molybdenum.

The wulfenite occurs always in clear crystals, their shapes being closely related to the acidity and oxidative character of the crystallization environment : most often in thin square tablets, and more rarely in elongated tetragonal octahedra, it is also rarely found in prisms or pseudo-cubes.

Wulfenite was first described in 1845 for an occurrence in Bad Bleiberg, Carinthia, Austria. It was named for Franz Xavier von Wulfen (1728–1805), an Austrian mineralogist.

Wulfenite with mimetite, Rowley Mine, Maricopa County, AZ. Wulfenite from Ojuela mine, Mapimi, Durango, Mexico Photo on the left:  Allans_minerals/IG Photo on the right: Exotic Crystals

Wulfenite has the composition PbMoO₄, and so belongs to an unusual class of minerals called “molybdates.” Minerals are divided into classes based on the composition of their anion group.

Wulfenite is found in the oxidation zone of lead deposits. Oxidation zones are home to some of the world’s strangest and most diverse minerals, as the influence of water and free oxygen interacting with the primary ore body create new and unique minerals.   

Other minerals associated with wulfenite in the lead ore oxidation zones are: pyromorphite, a bright green, barrel-shaped lead phosphate mineral; vanadinite, a deep crimson, lead vanadate mineral; and mimetite, an often bright yellow, lead arsenate mineral. Combinations of these lead oxidation minerals create  other-worldly color combinations, prized by collectors.

Molybdenum’s high melting temperature makes it a useful industrial metal. It is important in oil refinery and when alloyed with iron, increases the strength of steel. Although most molybdenum comes from the appropriately named mineral, molybdenite, wulfenite deposits can also be used as a minor ore of the metal.

Platy Crystals of Wulfenite Across the Top of This Matrix With Orange Mimetite From San Francisco Mine, Sonora, Mexico. Credit:  Weinrich Minerals, Inc

Wulfenite Properties

Composition: Wulfenite is a lead molybdate mineral. Its chemical formula is PbMoO₄, and it contains lead (Pb), molybdenum (Mo), and oxygen (O) as its main elements.

Color: Wulfenite typically displays a vibrant range of colors, including:

• Orange: Most common, ranging from pale yellow to deep red-orange.
• Brown: Due to iron impurities.
• Green: Rare, due to the presence of copper.
• Colorless: Very rare.

Transparency: Wulfenite can be transparent, translucent, or opaque, depending on the thickness and purity of the crystal.

Luster: Wulfenite exhibits a resinous to adamantine luster, meaning it appears waxy to glassy with a high brilliance.

Crystal System: Wulfenite crystallizes in the tetragonal crystal system

Streak: The streak of wulfenite is white.

Hardness: Wulfenite has a hardness of approximately 3.0 - 3.5 on the Mohs scale, meaning it can be scratched by a fingernail or steel knife.

Cleavage: Wulfenite typically exhibits Perfect cleavage in one direction, {001}. This means it can be easily split into thin sheets along specific planes.

Fracture: The fracture of wulfenite is Uneven to conchoidal.

Habits and Forms: Wulfenite typically forms tabular or prismatic crystals, often with pointed terminations. It can also occur in drusy masses, granular aggregates, and botryoidal forms.

Specific Gravity: The specific gravity of wulfenite ranges from approximately 6.7 - 7.0

Solubility: Insoluble in water but slightly soluble in acids.

Magnetism: Non-magnetic

Fluorescence: Some specimens of wulfenite may exhibit fluorescence under ultraviolet (UV) light. The fluorescence can vary, with colors such as yellow or orange.

Pleochroism: Weak pleochroism can be observed in some specimens, meaning the color appears slightly different depending on the viewing angle.

Refractive Index: The refractive index of wulfenite is High, ranging from 2.195 to 2.365.

Inclusions: Common inclusions include quartz, calcite, and other minerals.

Association: Cerussite, anglesite, smithsonite, hemimorphite, vanadinite, pyromorphite, mimetite, descloizite, plattnerite, Fe–Mn oxides.

Name: To honor Franz Xavier Wulfen (1728–1805), Austrian–German Jesuit, who wrote a monograph on the lead ores of Bleiberg, Austria.

Type Locality: Mining Academy, Freiberg, Germany.

Occurrence: A secondary mineral formed in the oxidized zone of hydrothermal lead deposits, the molybdenum commonly introduced externally.

Wulfenite specimens from Los Lamentos mine, Mexico   Photo: Marc Miterman

Uses and Applications of Wulfenite

Wulfenite, despite its relative scarcity and some toxicity due to its lead content, has several important uses:

Mineral Specimens and Collectibles: Wulfenite's vibrant colors and distinctive crystal habits make it highly sought after by mineral collectors. Specimens with well-formed crystals are particularly prized, and collectors often seek out specimens from renowned localities for their collections.

Ornamental Purposes: Some specimens of wulfenite, especially those with exceptional color and clarity, are used for ornamental purposes. They may be displayed as decorative pieces in homes, offices, or museums, adding natural beauty and aesthetic appeal to interior spaces.

Metaphysical and Spiritual Practices: In some spiritual and metaphysical traditions, wulfenite is believed to possess certain energies or properties that aid in personal transformation, manifestation, and spiritual growth. Practitioners may use wulfenite specimens during meditation, energy work, or ritual practices.

Lapidary Arts: Wulfenite, despite its relatively soft hardness, can be cut and polished to create cabochons, beads, and other lapidary items. Jewelry designers and artisans may incorporate wulfenite into their creations, though precautions should be taken due to its lead content.

Scientific Research: Wulfenite's crystal structure and chemical composition make it of interest to scientists and researchers studying mineralogy, crystallography, and geology. By studying wulfenite specimens, researchers can gain insights into geological processes, crystal growth mechanisms, and mineral formations.

Historical and Cultural Significance: Wulfenite, like other minerals, has played a role in human history and culture. It may have been used by ancient civilizations for decorative or ceremonial purposes, though specific historical uses are not well-documented.

Industrial Applications: While not as common as other minerals, wulfenite does have some industrial applications. It may be used in the production of lead and molybdenum compounds, though these uses are limited due to the mineral's scarcity and the potential environmental concerns associated with its lead content.

Overall, while wulfenite is primarily valued for its aesthetic qualities and its appeal to mineral enthusiasts, it also has cultural, spiritual, and scientific significance.

Wulfenite & Mimetite from San Francisco Mine, Mexico Credit: Mineral Masterpiece - Tom Spann

Occurrence and Distribution of Wulfenite

Wulfenite, a lead molybdate mineral, boasts a diverse geographic distribution, occurring in various geological settings worldwide. While not as abundant as some other minerals, its presence can be found in several notable locations:

United States: Notably present in Arizona, New Mexico, California, Nevada, Utah, and Idaho. Renowned localities include the Eureka Mine in Utah and the Mammoth-Saint Anthony Mine in Arizona.

Mexico: Chihuahua state harbors significant wulfenite occurrences, particularly in the Batopilas Mining District.

Austria: The Carinthian Mountains and Salzburg region offer wulfenite specimens, often associated with other minerals like quartz and calcite.

Germany: The Black Forest and Harz Mountains are home to wulfenite occurrences, sometimes found in association with barite and fluorite.

France: The Vosges Mountains and Massif Central region boast wulfenite deposits, occasionally accompanied by chalcopyrite and sphalerite.

Morocco: The Bou Azzer district and Mibladen area are known for their wulfenite occurrences, often found with vanadinite and mimetite.

Namibia: The Tsumeb Mine, renowned for its mineral diversity, also yields wulfenite specimens.

China: The Hunan and Jiangxi provinces harbor wulfenite occurrences, sometimes associated with galena and sphalerite.

Japan: The Hokuriku and Chugoku regions offer wulfenite deposits, often found with pyrite and chalcopyrite.

Australia: New South Wales: The Broken Hill district, famous for its mineral wealth, also contains wulfenite deposits.

Conclusion

Wulfenite's visual allure, historical significance, and varied uses contribute to its prominence in the world of minerals. As with many minerals, its properties make it a subject of interest for both collectors and researchers, highlighting the fascinating intersection of geology, chemistry, and aesthetics in the study of Earth's diverse mineral kingdom.

See also:
Vanadinite: Gemmy Mineral
Strengite Mineral Information
Chalcanthite: Facts About Chalcanthite