集块岩(英语：Agglomerate)是火山运动所产生的火成岩，通常为大型的火山物质的混合岩块，多见于火山活动的中心区域。它被定义为至少含75%的火山弹（Bomb）的岩石，通常为粗粒的混合质熔岩碎块混合在火山灰基质中。 堆积在火山口附近、覆盖于火山坡面或散布于火山附近之广大地区之火山碎屑物，凝固成大小不等之岩块，称火山碎屑岩(volcanic breccia)或集块岩(agglomerates)。集块岩中之大者比房子还大，小者可充填于大岩块之隙缝中。

Agglomerates (from the Latin 'agglomerare' meaning 'to form into a ball') are coarse accumulations of large blocks of volcanic material that contain at least 75% bombs. Volcanic bombs differ from volcanic blocks in that their shape records fluidal surfaces: they may, for example, have ropy, cauliform, scoriaceous, or folded, chilled margins and spindle, spatter, ribbon, ragged, or amoeboid shapes. Globular masses of lava may have been shot from the crater at a time when partly molten lava was exposed, and was frequently shattered by sudden outbursts of steam. These bombs were viscous at the moment of ejection and by rotation in the air acquired their shape. They are commonly 1 to 2 feet (30 to 60 cm) in diameter, but specimens as large as 12 feet (3.7 m) have been observed. There is less variety in their composition at any one volcanic centre than in the case of the lithic blocks, and their composition indicates the type of magma being erupted.