Valentinite with Arsenic, Silver

specimen number:
2262019

location:
St Andreasberg, Braunlage, Goslar, Lower Saxony, Germany

description:
Sparkling micro crystals of valentinite across this matrix of native arsenic with minor native silver. Classic material for this old locality. The specimen comes with an old label from the U. S. National Museum, ex Carl Bosch collection. This is shown at the end of the video.

St. Andreasberg, located in the Harz Mountains of Lower Saxony, Germany, is a historic mining district famous for its silver-rich vein systems. Geologically, the area is unique within the Harz because its mineralized veins are hosted in a specific block of Paleozoic rocks that were fractured and filled by hydrothermal fluids during the Permian and Triassic periods. Unlike other parts of the region, these veins are exceptionally rich in silver sulfosalts, arsenic, and antimony minerals, often occurring in carbonate-rich gangue. Mining history in the district dates back to the 15th century, with the most prosperous era occurring between the 16th and 18th centuries when the town was a major center for European silver production. The mines were famous for their depth and technical innovation, featuring complex water-management systems. Large-scale industrial operations eventually declined as the high-grade ores were depleted, and the last major mines closed their doors in 1910. Today, the district is celebrated as a classic mineral locality, especially for its historic specimens of pyrargyrite and calcite.

Valentinite is an antimony oxide mineral that typically forms as a secondary product in the oxidation zones of antimony-bearing ore deposits. It is known for its beautiful and delicate crystal habits, often appearing as bundles of prismatic, needle-like crystals or as fan-shaped aggregates with a distinct pearly to adamantine luster. The color is generally white, colorless, or pale gray, though it can sometimes show yellowish or brownish tints due to impurities. Geologically, it is created when primary minerals like stibnite are exposed to oxygenated water near the surface, causing the antimony to recrystallize into this more stable oxide form. St. Andreasberg is one of the classic localities for this species, where it was historically found in the upper levels of the silver mines. Because of its transparency and the elegant, silky appearance of its crystal groupings, valentinite is highly valued by collectors of rare secondary minerals.

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