Breccia rock is composed of larger gravel particle sizes. Breccia literally means rubble. Breccia consists of loose, angular fragments of minerals or rock cemented together by a fine-grained matrix. The angular shape implies that the fragments have not moved far from their source. Fragments are pea-sized and larger, similar to conglomerate. Commonly, breccias are found along fault zones.
Breccia can be divided into two broad classes:
- Clast supported where the clasts (fragments) touch each other.
- Matrix supported where the matrix (cement) surrounds each clast.
Breccias can be any color. Because it is clastic or coarse grained, it has a striking visual appearance that historically made it a popular material for sculpture and architecture. Most often it was used as an ornamental or facing material in walls and columns. Breccia can be soft to hard, dependent on clast composition and strength of cement. It can be used as dimension stone for decoration of walls and floors. Many types of marble are brecciated and the Romans regarded it as an especially precious stone, often used in high-profile public buildings.
Near Innsbruck, Austria, Hötting Breccia was quarried and used in the area for castles, churches and monasteries. Heavitree Breccia, near Exeter, England once provided large amounts of building stone for Exeter’s churches and public buildings. Today, suppliers from Egypt sell Green or Red Breccia in the form of raw blocks, slabs or tiles and large blocks of Breccia Pernice are quarried in Volargne, Italy.