2.95 ct DUFTITE ON MATRIX – USA

Duftite on Matrix

Duftite on Matrix is a gemstone of intense, “mossy” beauty that represents the lush side of the lead-copper oxidation zones. A lead copper arsenate, I have always admired it for its vibrant, olive-green to apple-green color, which often forms as a thick, velvety carpet of micro-crystals over a host rock. When it is found on a contrasting matrix—such as the dark, chocolate-brown Limonite or sparkling white Quartz—the visual effect is remarkably organic, resembling ancient moss growing on a stone. For me, Duftite is a stone of intricate textures; its botryoidal or “druzy” habit creates a soft, matte-to-vitreous luster that draws the eye into the minute details of its crystalline surface. It is a prize for the specialist who appreciates the complex chemistry of secondary minerals born from the weathering of primary ores.

The Heritage & Discovery

Historical Significance: Duftite is a vital species for understanding the behavior of arsenic in the “gossan” or iron-cap of ore deposits. Historically, it was often overlooked or mistaken for other green arsenates until its distinct structural identity within the Adelite-Descloizite group was confirmed. In the world of fine minerals, it is celebrated for its spectacular “crusts,” which can cover large areas of matrix, standing as a favorite for those who value high-contrast, “landscape” specimens. It serves as a symbol of the regenerative power of the oxidation zone, where the breakdown of harsh primary sulfides gives rise to delicate, vibrant new forms.

Discovery: The mineral was first described in 1920 and was named in honor of Gustav Duft (1855–1933), the Director of the Otavi Mining and Railway Company in Namibia. Its discovery in the legendary Tsumeb Mine provided mineralogists with a clear look at how lead, copper, and arsenic can stabilize into a beautiful, hydrated arsenate. Since its naming, it has become the definitive representative of its group for many collectors, particularly those focusing on the minerals of Africa and the American Southwest.

Important Mines: The undisputed world capital for the finest Duftite on Matrix is the Tsumeb Mine in Namibia. This site produced the iconic “velvet” green specimens that set the global standard. I also have a high regard for the sharp, crystalline material from the Ojuela Mine in Mapimí, Mexico, and the vibrant crusts from the Mt. Isa region in Australia. For the vault, I prioritize Tsumeb specimens for their historical pedigree and the Mexican pieces for their unique association with other rare minerals like Adamite or Wulfenite.

Mineralogical Profile

Description: Duftite is a lead copper arsenate hydroxide that crystallizes in the orthorhombic system. It sits at a 4.5 on the Mohs scale, making it a relatively soft mineral that requires careful handling to preserve its delicate, often microscopic crystal terminations. It is characterized by its vitreous to waxy luster and its range of green shades, from pale “pistachio” to deep “forest” green.

One of its most identifying traits is its habit—it almost always occurs as aggregates of tiny, indistinct crystals that form rounded, “bumpy” (botryoidal) surfaces or druzy coatings. It has a high refractive index ($n \approx 2.02$ to $2.08$), which gives the individual micro-facets a “snappy,” brilliant spark when viewed under magnification. Because it is a lead-bearing mineral, it is surprisingly heavy for its appearance ($SG \approx 6.4$). When I select a Duftite on Matrix, I look for a “vibrant” green color and a clean, undamaged matrix, as these specimens represent the species in its most aesthetic and desirable form. It is a dense, earthy mineral that remains a standout for its “neon-moss” personality.

Chemical Formula: PbCu(AsO₄)(OH)