A survey of clasts and large chondrules in ordinary chondrites

We report the results of a survey of clasts and large (>5 mm) chondrules (macrochondrules) within the 833 ordinary chondrites of the Natural History Museum collection. Thirty‐six macrochondrules and 24 clasts were identified and studied. Macrochondrules have textures and mineral assemblages like normal chondrules and so share a common origin. Clasts show evidence for fracturing from larger bodies and can be classified as either: (1) chemically fractionated if they have major and trace‐element compositions differing substantially from most chondrules and clasts; (2) impact melt clasts if they have microporphyritic textures and signs that indicate they are derived from shock‐melted chondritic material; (3) microporhyritic clasts if they are similar to the last category but lack evidence for derivation through shock melting; or (4) indeterminate clasts forming a diverse class that includes all those clasts that do not fit into the other categories.