Hematite after Magnetite

specimen number:
2072311

location:
Payun Volcano, Mendoza, Argentina

description:
Skeletal crystallized magnetite, this on a small amount of matrix and replaced by bright lustrous metallic crystallized hematite. In great condition.

The Payun Matru volcanic field, located in the Malargue Department of Mendoza Province, Argentina, is a vast basaltic plateau characterized by numerous cinder cones and extensive lava flows. Geologically, the area is part of the Andean back-arc volcanic zone, where recent quaternary eruptions produced a variety of volcanic rocks, including the massive Payun volcano. The locality is world-famous for its remarkable hematite after magnetite pseudomorphs, often referred to as martite, which occur as lustrous, black octahedrons that can reach several centimeters in size. These specimens formed when original magnetite crystals, precipitated from volcanic gases or within cooling lavas, were later oxidized to hematite while perfectly retaining the sharp, isometric crystal form of the magnetite. Historically, there has been no large-scale industrial mining or quarrying for metals at this site; instead, activity has been limited to the artisanal collection of mineral specimens, which began to reach the international market in significant quantities during the late 1990s and early 2000s. As of 2026, the region is protected as part of the Payunia Provincial Reserve, meaning that while it remains a type locality for these geometric treasures, modern specimen recovery is strictly regulated to preserve the unique volcanic landscape.

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