Evaporite encrustations and sulphide oxidation products from the southern Antarctic Peninsula

White evaporite encrustations collected from 66 sites scattered over 30 000 km 2 of southern Antarctic Peninsula are dominantly gypsum and calcite, and subordinate aragonite and thenardite. Natrojarosite occurs as locally developed yellow surface stains on approximately 30% of the white encrustations examined. Water, which forms by the melting of snow blown into cracks in highly fractured rocks by ground blizzards, dissolves soluble ions from minerals in these rocks as it percolates into them. The white encrustations appear to be deposited when this water later rises to the surface by capillary action and evaporates. Yellow surficial salts (alunite, fibroferrite, natrojarosite) collected at 5 sites form in place by the near‐surface oxidation of pyrite disseminated in the sedimentary and plutonic rocks. Green surficial salts (atacamite, antlerite, brochantite, plancheite) collected at 4 sites form in place by the near‐surface oxidation of copper sulphides under conditions of low acidity. This is the first reported occurrence of alunite, bronchantite, fibroferrite, and plancheite from Antarctica.