Hemimorphite

specimen number:
2133318

location:
Cho Dien Mine, Na Hang, Tuyen Quang, Vietnam

description:
Interesting old locality example, this banded crystalline hemimorphite with little attached matrix. The specimen comes with several previous labels as shown at the end of the video.

The Cho Dien mine district, situated in the mountainous Bac Kan Province of northeastern Vietnam, represents a major structural and economic hub within the prominent Lo Gam metallogenic zone. The regional geology is characterized by Lower Devonian sedimentary sequences composed of thick, gray limestones, marbles, dolomitic limestones, black bituminous mudstones, and shales. Intense structural deformation and regional fault intersections running north-south and northeast created conduit pathways for hydrothermal fluids, which deposited extensive, stratabound lead-zinc replacement bodies where sphalerite and galena serve as the primary ore minerals, alongside subordinate pyrite, pyrrhotite, and chalcopyrite. While ancient localized surface pitting occurred for centuries, industrial underground mining and open-cast quarrying operations were established under French colonial administration in the early 20th century, with heavy extraction accelerating by the 1910s and 1920s to export high-grade zinc and lead ores. Following a period of disruption during mid-century conflicts, operations were revitalized in the late 1950s and 1960s with technical assistance from Eastern European nations and China. The mining complex transitioned to state ownership under enterprise groups like the Thai Nguyen Nonferrous Metal Joint Stock Company, maintaining continuous deep underground extraction and modernized processing into the 2020s to supply essential zinc concentrates to domestic electrolytic factories.

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