An experimental study of the thermal history of fragment-laden 'basalt' 77115

Phase equilibrium and dynamic crystallization experiments using a synthetic analog of the 77115 matrix composition restrict interpretations of the thermal history of the lunar sample. Rapid early cooling (10-25 G/hr) of melt containing a large number of a nuclei and slow late stage cooling (less than 7 C/hr) are required to crystallize the textures and mineralogy of the 77115 matrix. This result is in agreement with that predicated by the nature and extent of diffusive cation exchange between various xenocrysts phases and the 77115 matrix.