The list attached contains physical properties (density, porosity, magnetic susceptibility, p-wave velocity and electrical resistivity) of seafloor massive sulphide, jasper and basalt samples. The seafloor samples have been obtained during cruise JC138, Mid-Atlantic Ridge, 26N (cruise report https://www.bodc.ac.uk/resources/inventories/cruise_inventory/report/16052/ ) in July 2016 and from onshore analogues. The data has been measured at the National Oceanography Centre under the lead of Dr Laurence North.

Supplement to: Gehrmann, Romina A S; North, Laurence J; Graber, Sebastian; Szitkar, Florent; Petersen, S; Minshull, Tim A; Murton, Bramley J (2019): Marine Mineral Exploration With Controlled Source Electromagnetics at the TAG Hydrothermal Field, 26°N Mid‐Atlantic Ridge. Geophysical Research Letters, 46(11), 5808-5816