A stony-iron meteorite is a meteorite composed of roughly equal amounts by weight of silicate minerals and nickel-iron. Modern meteoritics considers the stony-irons to consist of just two groups, the mesosiderites and the pallasites; however, there is a gradual shading into metal-rich stony meteorites such as the lodranites (once considered to be stony-irons) and silicate-rich iron meteorites. Stony-iron meteorites are less abundant than their stony and iron cousins, comprising a total known mass of some 10 tons – about 1.8% of the entire mass of all known meteorites.