matrice

CONT: Dans les gîtes où la minéralisation est contenue dans des brèches, les clastes sont constitués de fragments de roches hôtes et la matrice est riche en oxydes de fer.

CONT: Conglomerates ... consist of rounded pebbles, cobbles and boulders set in a fine-grained matrix. The matrix usually consists of sand or silt and is commonly cemented by calcite or quartz. In contrast, breccias contain angular rock fragments similarly set in fine-grained, sandy or silty matrix.
CONT: In breccia deposits, the clasts are fragments of the host rocks, and the matrix is rich in the iron oxides.