Gedrite

Classic radiating gedrite aggregates in matrix from the historic Stolberg Mine at Väster Silvberg, Dalarna, Sweden. The specimen displays elongated to fibrous black gedrite crystals arranged in distinct radiating sprays and bundles, sharply contrasting with the light-colored host rock. This texture is characteristic for gedrite occurrences in high-grade metamorphic environments.

Gedrite is a member of the amphibole group, specifically within the anthophyllite–gedrite solid-solution series, and is an aluminium-rich amphibole typically formed during regional metamorphism of aluminous, magnesium-rich rocks. At Väster Silvberg, gedrite formed under high-temperature amphibolite- to granulite-facies conditions, reflecting the complex metamorphic history of the Bergslagen ore province.

The Stolberg Mine is part of the famous Bergslagen mining district, one of Sweden’s most important historic mining regions, known primarily for iron, silver, and base-metal deposits. Although gedrite is not a primary ore mineral, specimens from this locality are valued by collectors for their well-developed radiating habits and strong locality significance.

Material from Väster Silvberg was mainly recovered during historic mining operations in the 19th and early 20th centuries, with additional specimens collected from mine dumps and surrounding outcrops. Today, classic specimens from Stolberg are infrequently available, especially in larger cabinet-size pieces with clear crystal structures.