Mesosiderites are a class of stony-iron meteorites consisting of about equal parts of metallic nickel-iron and silicate. They're breccias with an irregular texture; silicates and metal occur often in lumps or pebbles as well as in fine-grained intergrowths. The silicate part contains olivine, pyroxenes, and Ca-rich feldspar and's similar in composition to eucrites and diogenites. They're a rare type of meteorite; as of June 2009 only 145 are known (of which 44 come from Antarctica) and only 7… (More on Mesosiderite)