Piemontite with Hyalophane

specimen number:
9302296

location:
Jokkmokk, Norrbotten Co., Sweden

description:
Thick prismatic lustrous terminated crystal 2.2 cm in length on matrix with minor hyalophane. In very good condition.

The Jokkmokk area, situated within Norrbotten County in northern Sweden, encompasses several historical mining and quarrying districts noted primarily for iron, base metals, and industrial minerals. Geologically, the region lies within the Fennoscandian Shield and features Paleoproterozoic supracrustal rocks, including metavolcanics and metasediments, which were heavily intruded by syn-orogenic granites and pegmatites. Significant localized deposits, such as the nearby Kallak iron ore deposit and various historical skarn-type and pegmatitic prospects, formed through intense regional metamorphism and hydrothermal mineralization processes during the Svecokarelian orogeny. Small-scale mining and exploration for iron ore began in the seventeenth and eighteenth centuries, with more structured prospecting and quarrying ventures expanding in the late nineteenth and mid-twentieth centuries. While major industrial operations fluctuated depending on international markets, localized exploratory drilling, quartz quarrying, and mineral specimen collecting have continued intermittently across the municipal district well into the twenty-first century.

Piemontite is a manganese-rich sorosilicic mineral belonging to the epidote group. It typically occurs as an essential or accessory component in low-to-medium-grade metamorphic rocks, such as schists and gneisses, as well as in hydrothermally altered volcanic rocks. The mineral is distinguished by its deep red, purplish-red, or reddish-brown coloration, which results from the replacement of aluminum or trivalent iron by manganese within its crystal structure.

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