Mid-ocean-ridge basalts recovered from Hole 1256D during Ocean Drilling Program Leg 206 exhibit the effects of various low-temperature (<100°C) alteration processes, including the formation of black or dark green alteration halos adjacent to celadonite-bearing veins. In several samples from the deepest basalts, a Ti-rich hydrogarnet occurs. To our knowledge, such a mineral has never been reported in the oceanic crust. This report presents a brief description and microprobe analyses of this hydrogarnet and associated celadonite. More detailed characterizations of this mineral and a description of its relationship to other secondary minerals will be undertaken in a future study, in an attempt to determine the mineral's formation conditions and its place in the general alteration history of the Hole 1256D basalts.

Supplement to: Laverne, Christine (2006): Data report: Chemical composition of unusual Ti hydrogarnets from the deepest volcanic rocks cored in ODP Hole 1256D (Leg 206). In: Teagle, DAH; Wilson, DS; Acton, GD; Vanko, DA (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 206, 1-6