1.25 ct LINDGRENITE ON MATRIX – USA

Lindgrenite

Lindgrenite is a striking example of the rare and vibrant chemistry found in the oxidation zones of molybdenum-rich copper deposits. It presents with a distinctive, intense yellowish-green color that feels almost “electric” against the darker host rocks. As another featured mineral in my micro-crystal matrix series, Lindgrenite required an incredibly delicate touch. These crystals often form as thin, transparent plates or tablets, and because of their rarity and small size, traditional cutting would be nearly impossible. By faceting them directly in the matrix, we have managed to showcase their brilliant, vitreous luster and tabular geometry, turning a specialized mineralogical specimen into a truly unique, “earth-mined” gemstone.

The Heritage & Discovery

Historical Significance: Lindgrenite is a rare secondary mineral that serves as a fascinating marker for the geochemistry of molybdenum and copper. It represents a specific environment where these two metals oxidize in a neutral to slightly acidic setting. For collectors, it is a “refined” rarity—it doesn’t have the bulk of common minerals, but its color and crystalline habits are instantly recognizable to those who know the world of specialized silicates and molybdates. It stands as a testament to the complex chemical evolution that occurs within the crust of our planet.

Discovery: The mineral was first described in 1935 and was named in honor of Waldemar Lindgren (1860–1939), a world-renowned Swedish-American economic geologist and professor at MIT. Lindgren was a pioneer in the study of ore deposits, and naming this rare molybdate after him was a fitting tribute to his work in mapping the very types of deposits where this mineral is found.

Important Mines: The type locality for Lindgrenite is the Chuquicamata Mine in the Antofagasta Region of Chile. This massive copper mine is legendary for its complex secondary mineralogy. Other significant occurrences have been found in the Seven Devils district in Idaho, USA, and certain mines in Arizona. We look for matrix specimens from these arid, high-altitude environments because they tend to produce the sharpest, most transparent green plates, perfect for our matrix-faceting technique.

Mineralogical Profile

Description: Lindgrenite is a copper molybdate hydroxide that crystallizes in the monoclinic system. It sits at a 4.5 on the Mohs scale, making it a soft collector’s mineral that is quite brittle. It is characterized by its thin, tabular crystal habit and its vibrant green to yellowish-green color. The luster is vitreous to slightly greasy, and when the faces are polished through our matrix method, they exhibit a crisp transparency that reveals the stone’s inner glow. It is also pleochroic, meaning it can show slightly different shades of green depending on the angle of the light.

Chemical Formula: Cu₃(MoO₄)₂(OH)₂