Munakataite

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Formula: Pb₂Cu₂(Se⁴⁺O₃)(SO₄)(OH)₄
Valence: Pb²⁺₂Cu²⁺₂(Se⁴⁺O₃)S⁶⁺O₄(OH)₄
Selenite of lead and copper, linarite-chenite group
Crystal System: Monoclinic
Specific gravity: 5.526 calculated
Hardness: 2½
Streak: Bluish white
Colour: Light blue
Luminescence: Not fluorescent under UV
Environments

Hydrothermal environments

Localities

At La Vidale mine, Asprières, Villefranche-de-Rouergue, Aveyron, Occitanie, France, munakataite has been found on quartz (Mindat photo).
Munakataite from La Vidale mine - Image

At the type locality, the Kato mine, Munakata City, Fukuoka Prefecture, Japan, munakataite occurs as a thin coating on a fracture in a quartz vein containing Cu-Zn-Pb-Ag-Au ore minerals at a mine dump. It exists as aggregates composed of minute fibrous crystals up to 30 microns long. The hydrothermal ore veins develop into a tertiary porphyritic andesite. The main ore minerals are electrum, chalcopyrite, sphalerite and galena as well as hessite and sylvanite as minor constituents.
The secondary minerals such as cerussite, anglesite, linarite, pyromorphite, malachite and brochantite are abundant. Munakataite occurs with malachite or alone on a tiny fracture of quartz (Journal of Mineralogical and Petrological Sciences 103.5.327-332).
Munakataite from the Kato Mine - Image

At the Tsumeb Mine (Ongopolo Mine), Tsumeb, Oshikoto Region, Namibia, munakataite occurs in association with other rare minerals that contain essential selenium, including plumboselite, clausthalite and orlandiite. The matrix of the specimen comprises mimetite, smithsonite, galena and quartz. Selenium is a moderately scarce element at Tsumeb, and prior to the discovery of munakataite only three minerals containing essential selenium had been reported, namely clausthalite, plumboselite and umangite (R&M 91.6.548-553).
Munakataite from the Tsumeb Mine - Image

At Otto Mountain, San Bernardino County, California, USA, munakataite has been found in association with a variety of rare secondary tellurium minerals. It is very rare and occurs as subparallel bundles of blue needles up to 1 mm long (MM 74.6.991-998).
Munakataite from Otto Mountain - Image

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