Diaboleite

Diaboleite occurs in manganese oxide ores, as a secondary mineral in lead and copper oxide ores, and in seawater-exposed slag. Diaboleite has been found in association with atacamite, boleite, caledonite, cerussite, chloroxiphite, hydrocerussite, leadhillite, mendipite, paratacamite, phosgenite, and wherryite. A study in 1986 synthesized diaboleite crystals up to 0.18 mm (0.0071 in) in size using two different methods. The study demonstrated that diaboleite is a low-temperature phase, that is stable under hydrothermal conditions at temperatures less than 100 to 170 °C (212 to 338 °F). At higher temperatures, the first stable mineral to form is cumengeite.

In 1923, diaboleite was discovered at Higher Pitts Mine in the Mendip Hills of Somerset, England, and described by L. J. Spencer and E.D. Mountain. The study of the similar mineral boleite was perplexing at the time and this new mineral only compounded the difficulty. As insufficient material was available for a full investigation, Spencer and Mountain named it diaboleite, meaning "distinct from boleite", out of "desperation". The mineral was grandfathered as a valid mineral by the International Mineralogical Association as it was described prior to 1959.

As of 2012, diaboleite has been found in Australia, Austria, Chile, France, Germany, Greece, Iran, Italy, Russia, South Africa, the UK and the US. The type material is held at the Natural History Museum in London and the National Museum of Natural History in Washington, D.C.