Mercury (element) long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by Joseph Priestley in an early synthesis of pure oxygen. Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver. Being a soft metal, mercury forms very stable derivatives with the heavier chalcogens. Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore cinnabar and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two forms, the reddish cubic form and the black zinc blende form. The latter sometimes occurs naturally as metacinnabar. Mercury(II)
Glassworks Museum of the Ore Mountains in 1750, of Purschenstein Castle was placed under protection. Through grants the house, which is owned by the parish, was refurbished and, with the help of the local branch of the Ore Mountain Club, turned into a museum. In May 1996 the Ore Mountain Glassworks Museum ("Erzgebirgische Glashüttenmuseum") opened its first exhibition. It contained pieces from the roughly 800-year-old glassmaking industry in the Ore Mountains. The exhibition focusses particularly on the history of the Heidelbach Glassworks from 1488 to 1827. Since opening, the museum has also been enhanced by the replica of a glass melting furnace in an adjoining building,